Tag: Fish Profiles

In my years working with rainbowfish, boesemani Rainbowfish at the pet store look nothing like adults. The washed-out silver juvenile turns into a half-blue, half-orange showpiece over months. But they need space, schools of 6 or more, and hard water.

Juvenile boesemani look nothing like the adults on the box. Patience is the price of those colors.

A mature male boesemani in breeding color rivals most saltwater fish for impact. You just have to wait for it.

Table of Contents

• Overview Of The Fish Species
• What Most Care Guides Get Wrong
• Classification
• Introduction To Boesemani Rainbowfish
• Origin and Habitat
• Appearance
• Boesemani Rainbowfish Care
• Food and Diet
• Breeding Boesemani Rainbows
• Conclusion
• Is the Boesemani Rainbowfish Right for You?
• Species Comparison

Boesemani rainbowfish are one of my go-to recommendations when people ask about community fish that actually look impressive in a planted tank. That blue-purple to orange gradient is genuinely striking. Especially when you have a school of 8 or more males competing and displaying. They’re one of those fish that look like they cost a lot more than they actually do.

They’re peaceful, reasonably easy to keep, and get more beautiful as they mature and fully color up. Here’s what it takes to keep them healthy and showing full color.

What Most Care Guides Get Wrong About Boesemani Rainbowfish

Most guides give you a cookie-cutter care sheet for Boesemani Rainbowfish without mentioning the nuances. After 25+ years in this hobby, I have seen how small details in tank setup and maintenance make a real difference in long-term health. Another thing guides gloss over is temperament. Boesemani Rainbowfish are often described with a single label, but their behavior shifts depending on tank size, tank mates, and territory. You need to plan for the worst-case scenario, not the best. Group size is another area where most guides fall short. Saying ‘keep them in groups’ is not enough. The difference between keeping 3 and keeping 8 or more is night and day when it comes to coloration, confidence, and natural behavior.

Overview Of The Fish Species

Classification

Introduction To Boesemani Rainbowfish

Everybody has tetras in their tank. We don’t blame them. Tetras are small yet colorful fish that can make any tank come to life.

But isn’t there another, more unique alternative that’s just as colorful and exciting?

Yes! Past the tetras and the rasboras, there’s a wide variety of rainbowfish species available for beginner to expert hobbyists. These fish have all the characteristics that make tetras desirable but offer a new shape and personality to the community fish tank. The Boesemani rainbowfish, scientifically known as Melanotaenia boesemani, is one of the most popular species of rainbowfish available in the aquarium hobby.

Though these fish are very popular in the hobby and have been successfully bred commercially, they are, unfortunately, endangered in their wild natural habitat ecosystems and listed on the IUCN Red List of endangered species. This is a direct result of harvesting done by the aquarium hobby, so it is strongly encouraged to ethically source the next rainbowfish that you add to your tank.

Otherwise, rainbowfish are large, active schooling fish that is kept in moderately sized aquariums. They get along with most freshwater community fish species and are hardy to most aquarium water parameters.

Origin and Habitat

The Boesemani rainbowfish is one of the most colorful species of fish that occurs naturally in the wild. These blue and orange fish have a very limited natural range, with populations existing only in the tri-lake region of Indonesia known as Ajamaru. Some other populations have been found in nearby lakes, namely Lake Hain and Lake Aitinjo.

There, Boesemani rainbowfish stay in the shallow waters. They is found in dense vegetation where they school and reproduce. Though the waters from these lakes are naturally hard with high pH, Boesemani rainbowfish have been found in various hardness and pH conditions. This has made acclimating them to the water parameters preferred by aquarium fish that much easier.

As we’ll see, these fish do best in heavily planted aquariums with low to moderate water flow.

Appearance

Rainbowfish have unique appearances that make them attractive to hobbyists who want something a little different from your typical tropical fish. There are many different species of rainbowfish available, with some staying small and others growing large with special features.

The true appeal of this rainbowfish is its colors. There is no other fish that compares! The Boesemani rainbowfish is brightly colored with blues, yellows, oranges, and even greens. Male Boesemani rainbows feature the greatest contrast in colors, with the first half of their body being a dark blue that slowly fades into a deep orange by their tail fin. In contrast, females are solid silver or yellowish-green with lighter-colored bellies.

The Boesemani rainbow also has an interesting body shape. They have a deeper body with long dorsal and anal fins. Female fish aren’t as deep-bodied, but can still easily be told apart from other species.

Boesemani Rainbowfish Care

Boesemani rainbowfish care is easy, though there are some special considerations that should be taken into account before buying them. If given the right aquarium setup, though, these fish can live for relatively long times and will bring new colors to a fish tank.

Are They Easy To Keep?

In general, Boesemani rainbowfish are very easy to keep: they’re hardy fish that have been bred to withstand most conditions seen in the aquarium hobby. However, they are large, active fish that will be overbearing for other species.

Despite their larger size, they can also be somewhat skittish fish. Because of this, it’s essential to keep them in sizeable groups with an appropriate ratio of female to male fish. This grouping setup will also help increase color expression from the males while also lessening the harassment between males and females.

To help make your fish even more comfortable in its tank, a heavily planted setup is recommended.

Aquarium Setup

Unlike tetras and other popular tropical fish, Boesemani rainbows should be given some special consideration when setting up their tank. These fish shine best when given the right conditions.

An ideal Boesemani aquarium setup would be filled with dense vegetation at all levels of the aquarium. These fish mostly swim in the middle but will gladly venture to the tops and bottoms of the tank to look for food. To help make them more comfortable, add live plant species that grow in the foreground, midground, and background. Otherwise, regularly prune plants to create a layered effect.

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Rocks, driftwood, and other natural aquarium decorations may be added to create depth and interest as well as various hiding spots for your fish. Make sure to keep plenty of space open in the middle of the tank as these rainbows like to swim! While unlikely to jump out of the aquarium, it’s recommended to use an aquarium lid that stops any overly adventurous fish.

Tank Size

We list Boesemani rainbowfish as moderately difficult fish to keep due to their relatively demanding tank size. These are larger-than-average tropical fish that need plenty of room to swim and school. That being said, they don’t require a massive setup, either.

Boesemani rainbowfish need a minimum tank size of 40 gallons. Any smaller than this reduces the number of rainbows that is kept together and the other species that is added. Any aquarium larger than this greatly increases the possibility of keeping other rainbows and species.

Remember that a lot of aquarium space will be lost to plants and decorations in a heavily planted tank.

Water Parameters

Boesemani rainbows are hardy fish. They’ve been successfully bred in the aquarium industry, meaning they have been comfortably kept in many different water parameters. This also means that they’ve been exposed to many common freshwater diseases, helping their immune systems recognize and overcome pathogens faster and easier.

These rainbowfish do best when kept in tropical water conditions with a constant water temperature between 72. 77° F. While a tropical species, hobbyists report having greater success keeping their Boesemanis in slightly cooler water temperatures.

As mentioned before, Boesemani rainbowfish have been found in varying pH levels. In general, the aquarium should be kept at neutral pH, between 7.0. 8.0. Water hardness should remain between 9. 19 KH, but they are highly adaptable to changing hardness levels as well.

Filtration and Aeration

Boesemani rainbows don’t mean to be messy, but their size, activity, and willingness to eat anything can make for a high bioload. Luckily, plants help uptake nutrients and other wastes to perform food production. This reduces the need for extensive tank maintenance, though some care is still needed.

An adequately sized filter is highly recommended for a Boesemani rainbowfish tank. This filter should be rated for at least 2x the tank size to help remove waste and provide water circulation. These rainbows are strong swimmers and are able to swim against a moderate water flow but need areas of lower flow. Consider the types of live plants you plan on keeping too. Many species prefer gentle water movement.

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Additional aeration is always welcomed and is achieved through a sponge filter and/or air stone. A large sponge filter or several smaller ones can create low water movement while also facilitating gas exchange, which is important for plant health. An air stone can also be attached to an air pump for aesthetic purposes or for better gas exchange.

Lighting

The type of lighting you need for your tank depends on the types of plants being kept. Boesemani rainbowfish is skittish with other active species and sudden shadows, but they can be kept under higher lighting setups as long as an aquarium lid is secured. In other words, these rainbows won’t avoid swimming out in the open just because of high lighting conditions.

Instead, base the amount of lighting on the species of live plant being kept. Even with high lighting, rainbowfish will use their natural habitat to hide if they feel uncomfortable or stressed; if you do find that your fish is hiding in the shadows, try adding more live plants, floating plants, or structures to increase available areas for relief.

Aquarium Plants and Decorations

Aquarium plants are a must for Boesemani rainbows. These fish originate from very densely planted areas which provide them with food and shelter. It seems counterintuitive, but the more places you have available for your fish to hide, the more likely they’ll be out in the open.

Aquarium plants also make for a healthy tank. In order to perform photosynthesis and grow, plants need nutrients. The fish and invertebrates provide these nutrients in the aquarium. As these excess nutrients are used, the water is cleaned, meaning less work for the hobbyist. This also means that additional fertilization may be necessary if enough nutrients aren’t naturally entering the system.

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In addition to plants, rocks, and driftwood, other aquarium-safe decorations may be added to your rainbowfish tank. Make sure that these objects are securely placed, as Boesemanis can bump into them and knock them over when going at high speeds.

Tank Maintenance

Because most rainbowfish are kept in well-planted tanks, tank maintenance is low. In fact, some aquarium keepers leave their Boesemani tanks unfiltered, leaving the live plants and fish to find a balance between nutrient input and output; we only recommend this Walstad method for very experienced hobbyists.

Still, regular weekly or biweekly 10-25% water changes are recommended. Performing water changes helps remove waste caught around the stems of plants while also introducing new, nutrient-rich water for plants to use. If using a pure source of water, like from reverse osmosis, then minerals will need to be manually added back in.

If dosing fertilizers, regularly use a dependable water testing kit to see how nutrients are moving throughout the system.

Substrate

Boesemani rainbowfish is kept on any substrate. A dark substrate will help complement and intensify their coloration but it isn’t necessary to make these fish bold.

Instead, the substrate should be chosen with plants in mind. For this reason, many hobbyists use plant-specific substrates that facilitate healthy root growth. Another good alternative is aquarium-purpose river sand that comes in various color grades.

Community Tank Mates

For the most part, Boesemani rainbowfish are peaceful fish that is kept with various species. The main concerns in choosing suitable tank mates for them are matching preferred water temperatures and activity levels.

Can They Go In A Community Tank?

Yes! Boesemani rainbows thrive in a community tank setting. They are often used as the featured species of the tank, with all other fish complimenting their movement and colors.

Some of the best Boesemani rainbowfish tank mates include:

• Larger tetras
• Larger rasboras
• Corydoras
• Barbs
• Other rainbowfish

Because these rainbows prefer harder water, experienced keepers have had luck keeping them with some of the more peaceful species of African rift lake cichlids. Avoid smaller, slow-moving fish tank mates that could easily be overwhelmed and outcompeted.

Boesemani rainbowfish are schooling fish that love to be in their own company. However, an imbalance of males to females can lead to harassment, so it’s recommended to keep 2 to 3 females for every male fish. At least 6 rainbowfish should be kept together at any given time.

Food and Diet

These rainbows happily accept any and all foods. They are active swimmers that need a lot of food to keep them going. A small portion of high-quality flake food may be given a couple of times throughout the day. This will help keep costs down while also encouraging your fish’s colors while fulfilling their appetite.

For a treat, Boesemani rainbowfish may be given a mixed diet of freeze-dried, live, and frozen foods. They especially love brine shrimp, bloodworms, tubifex worms, and mosquito larvae. As omnivores, they will also eat green vegetables, like spinach and cucumber. While these rainbows aren’t overly messy fish, regular feedings of protein-rich food can lead to water quality issues.

While Boesemani rainbows might seem like they have large mouths, they actually have small throats, which can limit what they eat. Make sure to feed appropriately-sized live foods and cut up any pieces that might seem too big.

Another concern with Boesemani feeding is that they are too ambitious. These are fast fish and even faster eaters. This can cause other fish to miss out and become stressed. To help mitigate this problem, try feeding Boesemanis sinking foods and the other fish floating foods. This should help keep all fish occupied with eating at different levels of the tank.

Breeding Boesemani Rainbows

Breeding Boesemani rainbowfish has been achieved at the commercial level. They are easy to breed in the home aquarium setting though it’s recommended to use a breeding tank. Raising their fry is somewhat challenging, and a breeding tank will provide the most control over conditions.

To start breeding your Boesemani rainbowfish, place a group of females with one to two males. Feed high-quality food and a steady diet while raising the water temperature to about 80. 84° F and pH to slightly basic at 7.5. When ready, females will become plump, and males will intensify in color.

As egg scatterers, female Boesemanis will freely release their eggs, and the males will fertilize them. Fine-leaved plants, like Java moss, or egg crate, is used to catch the eggs. Once the eggs have been fertilized, the adult fish may be removed from the tank to prevent them from eating the eggs.

After about a week, the fry hatch. They will need to be given small foods, like infusoria, until they’re big enough to accept bigger foods, like baby brine shrimp. After a few months, they are ready to be given to another hobbyist or moved back to the display tank.

Conclusion

Boesemani rainbowfish are great fish for hobbyists looking for something new. These fish are just as easy as tetras and rasboras but offer new colors and shapes to add to the community fish tank setup. There are a few considerations needed when picking tank mates, as these rainbows is overly active and ambitious feeders, but they are not aggressive. They are also easy fish to breed for beginner hobbyists looking for a new challenge!

Molly Fish tank mates need to handle hard, alkaline water. That eliminates most soft water species immediately. The number one mistake is mixing them with fish that need the opposite water chemistry. I’ve seen molly communities that thrived for years and some that fell apart fast, the difference was almost always stocking density and water chemistry compatibility, not temperament.

Pick tank mates that thrive in the same water as mollies. Do not force soft water fish into hard water.

Choosing Molly Fish Tank Mates – What You Need To Know

Choosing the best tank mates for molly fish is all about understanding their needs and the other species you want to add to their tank. We’ll be covering some amazing fish species later in this post, but let’s start by going over the thought process for choosing great tank mates.

Temperament

Some fish are more aggressive than others, so it’s important to choose fish with similar levels of aggression.

Molly fish are peaceful but not shy. They can hold their own with fairly boisterous fish but should not be kept with aggressive fish or larger predatory species.

Mollies are livebearers. They will eat their own young, but so will most other tank mates, so it is best to set up a breeding tank if you plan on breeding molly fish (video source).

Mollies are peaceful, but they will often eat shrimp. You could try to keep them together in a heavily planted tank with loads of hiding spaces, however.

Size

There is a general rule in the fish-keeping hobby. If a fish can fit in another fish’s mouth, they are not safe tank mates!

Mollies grow from 4-6 inches long and are certainly capable of eating very small, slow-moving fish. Likewise, large fish can easily snack on your mollies. Choose similar-sized fish, although fast schooling fish like neon tetras are safe.

Competition

Molly fish are hardy and have a very healthy appetite. They are not likely to be outcompeted for food at meal times, but you might need to make sure other shy species are getting their fair share.

Parameters & Tank Setup

It is vitally important to compare the preferred water parameters of different fish before adding them together in a community fish tank. Some fish have very specific needs and just won’t survive in typical tropical fish tanks. In my experience managing fish stores, the molly-and-soft-water mix was one of the most common mismatches we’d see, looked fine for a month, then started falling apart.

Let’s take a look at the recommended water parameters for your molly fish:

• pH: 7 – 8.5
• Water Temperature: 68 – 82°F
• Minimum Tank Size: 15 gallons (29 gallons+ recommended)
• Water Flow: Low-Moderate

Molly fish can live in saltwater, but most other fish aren’t so flexible, so never mix fresh and saltwater fish in the same tank. At the stores I managed, we kept molly display tanks in hard, alkaline water and they were consistently some of the healthiest, most active tanks on the floor.

15 Greatv Aquarium Mates

Having considered all the information above, it’s time to dive in and meet 15 awesome freshwater fish that you can keep with mollies.

Let’s get started!

Expert Take

After 25+ years in the hobby and running aquarium retail, I’ve watched more molly tanks go sideways from bad stocking decisions than from any disease or water quality issue. Mollies are one of the most adaptable livebearers in the hobby, they’ll even tolerate brackish conditions, but they need hard, alkaline water to thrive long-term. That water chemistry requirement is what limits their community options. Most soft-water tropical species will appear healthy in the same tank short-term, but one parameter will always be compromised. The best molly tank is a livebearer community, not a mixed community. I’ve kept mollies with every fish on this list at some point, they’re genuinely one of the more forgiving community fish out there, as long as you get the water chemistry right. — Mark Valderrama, AquariumStoreDepot

Quick-Reference Comparison Table

1. Dwarf Gourami

Ease: 6/10. Works, but requires more careful management.

Dwarf Gourami in Aquarium” class=”wp-image-549383″/>

• Scientific Name: Trichogaster lalius
• Origin: Bangladesh, India, Pakistan
• Minimum tank size: 15 gallons
• Care Level: Intermediate
• Swimming Level: All levels
• Adult Size: 2 inches
• Water Temperature: 72 – 82 °F
• pH: 6 – 8
• Diet: Omnivore

The dwarf gourami is a peaceful community fish with an interesting look. A pair of these colorful labyrinth fish would make a great addition to your molly fish community tank.

Dwarf gouramis are relatives of the betta fish. They come in some amazing colors, including neon reds, blues, and orange tones. They are fairly shy and will do best in a planted aquarium.

2. Guppy

Guppy Fish

An undemanding fish that is a livebearer. Many varieties available

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• Scientific Name: Poecilia reticulata
• Origin: Northeast South America
• Minimum tank size: 10 gallons
• Care Level: Easy
• Swimming Level: All levels
• Adult Size: 1.75 inches
• Water Temperature: 64 – 82°F
• pH: 5.5 – 8
• Diet: Omnivore

Guppies are ideal tankmates for your molly fish. Guppy fish are basically, the smaller, more colorful cousin of the molly fish. They are very easy to care for and will add loads of life to your tropical fish tank.

Guppy fish are livebearers, just like mollies. They will breed regularly in your aquarium, although the fry are not likely to survive the hungry mouths of their larger tank mates.

3. Platy

Ease: 9/10. One of the safest choices for this tank setup.

• Scientific Name: Xiphophorus maculatus
• Origin: Mexico & Central America
• Minimum tank size: 10 gallons
• Care Level: Easy
• Swimming Level: All levels
• Adult Size: 2 inches
• Water Temperature: 64 – 77 °F
• pH: 7 – 8.2
• Diet: Omnivore

Platy fish are another small livebearer that are peaceful tank mates for mollies. There are many different platy breeds, often with bold shades of yellow, orange, and black. These undemanding fish are a great choice for a mixed livebearer tank.

4. Neon Tetra

Ease: 9/10. One of the safest choices for this tank setup.

Neon Tetra

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• Scientific Name: Paracheirodon innesi
• Origin: South America
• Minimum tank size: 10 gallons
• Care Level: Easy
• Swimming Level: Middle
• Adult Size: 1.25 inches
• Water Temperature: 68 – 78 °F
• pH: 5 – 7
• Diet: Omnivore

Neon tetras add a burst of bright color and activity to any freshwater tropical aquarium. These small schooling fish are peaceful and very easy to care for.

Neon tetras prefer a lower pH than mollies, so they are not recommended for tanks with a pH over 7. These tiny tetras are strictly schooling fish, so make sure you pick up a group of at least 6 to 10.

5. Cardinal Tetra

Ease: 6/10. Works, but requires more careful management.

Cardinal Tetra

A very popular schooling fish. Looks like the Neon Tetra, but with longer blue and red stripes. Grows larger than a neon tetra as well

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• Scientific Name: Paracheirodon axelrodi
• Origin: South America
• Minimum tank size: 10 gallons
• Care Level: Intermediate
• Swimming Level: Middle
• Adult Size: 2 inches
• Water Temperature: 73 – 81 °F
• pH: 5.5 – 7.5
• Diet: Omnivore

The Cardinal tetra is another brightly colored tetra species from South America. They are a slightly larger and even more colorful relative of the neon tetra. These peaceful fish are a little more challenging to care for, and also come with a higher price tag.

Cardinal Tetras reward the fishkeeper with amazing colors and a peaceful attitude. They make a wonderful tank mate for molly fish.

Hard Rule: Never mix mollies with discus, German blue rams, or other soft-water South American species. The water parameters that keep mollies healthy (pH 7.5–8.5, hard water) are incompatible with the parameters those fish need. One group will always be stressed.

6. Endler’s Livebearers

Ease: 9/10. One of the safest choices for this tank setup.

Endler's Livebearers

A very active and colorful livebearer. Smaller in size than guppies

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• Scientific Name: Poecilia wingei
• Origin: Venezuela
• Minimum tank size: 10 gallons
• Care Level: Easy
• Swimming Level: All levels
• Adult Size: 1 inch
• Water Temperature: 75 – 86 °F
• pH: 7 – 8.5
• Diet: Omnivore

Endler’s livebearer fish are very similar to guppies, but do not grow as large and have different markings and fins. Endler’s livebearer fish are very confident, even though they are small fish. These peaceful nano fish make some of the best tank mates for mollies.

7. Otocinclus Catfish

Ease: 6/10. Works, but requires more careful management.

Otocinclus Catfish

A small algae-eating fish. Also great with freshwater shrimp.

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• Scientific Name: Otocinclus spp.
• Origin: South America
• Minimum tank size: 10 gallons
• Care Level: Intermediate
• Swimming Level: Bottom & Glass
• Adult Size: 2 inches
• Water Temperature: 74 – 79 °F
• pH: 6 – 7.5
• Diet: Algae

Otos are nano catfish that do a very important job in the aquarium. They are super-peaceful, and one of the only fish that will not eat your molly fry.

These tiny fish eat algae on the glass and other surfaces in your aquarium to keep the tank looking neat and clean.

8. Zebra Danio

Ease: 9/10. One of the safest choices for this tank setup.

• Scientific Name: Brachydanio rerio
• Origin: India
• Minimum tank size: 20 gallons
• Care Level: Easy
• Swimming Level: All levels
• Adult Size: 2 gallons
• Water Temperature: 64 – 75 °F
• pH: 6.5 – 7.5
• Diet: Omnivore

Zebra danios are very fast and hardy tropical freshwater fish. These active community fish are great for adding heaps of movement to any community tank.

Zebra danios are peaceful fish that will thrive on the same food and care as their live-bearing tank mates.

9. Siamese Algae Eater

Ease: 6/10. Works, but requires more careful management.

Siamese Algae Eater

A great algae-eating fish that is known for eating black beard algae. Grows up to 7 inches in length and requires a larger aquarium

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• Scientific Name: Crossocheilus siamensis
• Origin: Southeast Asia
• Minimum tank size: 30 gallons
• Care Level: Intermediate
• Swimming Level: Bottom
• Adult Size: 6 inches
• Water Temperature: 75 – 79 °F
• pH: 6.5 – 7
• Diet: Omnivore

The Siamese algae eater is another excellent molly fish tank mate. Choose this peaceful fish species for keeping your tank clean and adding activity. Fish keepers also appreciate their ability to devour black beard algae (BBA) – something that very few aquarium fish will eat!

Siamese algae eaters are very fast, active fish that will also enjoy prepared fish food like flakes and pellets. They grow up to 6 inches and they should be kept in school of at least 4 so keep them in a tank of 30 gallons or more.

10. Cory Catfish

Ease: 9/10. One of the safest choices for this tank setup.

• Scientific Name: Corydoras spp.
• Origin: South America
• Minimum tank size: 10 – 30 gallons depending on fish species
• Care Level: Easy
• Swimming Level: Bottom
• Adult Size: 1 – 3 inches
• Water Temperature: 74 – 80 °F
• pH: 7 – 8
• Diet: Omnivore

The corydoras catfish is a great addition to any peaceful community tank. These small bottom dwellers are super peaceful and will not bother your molly fish at all. Cory cats are very social fish, so you’ll need a school of at least 6 of the same species to see them acting at their confident best.

Cory catfish come in tonnes of different species, ranging from the tiny midwater schoolers like the dwarf cory to the regular-sized species like bronze, Sterba’s, and panda cories.

11. White Cloud Mountain Minnow

Ease: 9/10. One of the safest choices for this tank setup.

White Cloud Mountain Minnow

A very peaceful fish that does well in coldwater fish. Other minnow varieties are also available

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• Scientific Name: Tanichthys albonubes
• Origin: China
• Minimum tank size: 10 gallons
• Care Level: Easy
• Swimming Level: Upper/Middle
• Adult Size: 1.5 inches
• Water Temperature: 64 – 72 °F
• pH: 6- 8
• Diet: Omnivore

White cloud mountain minnows are excellent community fish for cooler water conditions. These graceful schooling fish tend to hang out in middle to upper layers of the water column.

White clouds are easy to care for and come in a cool long-finned variety as well as a gold color morph. They will not make good tank mates with tropical fish but they will be happy at 68 – 72 degrees which is the lower limit for your molly fish.

12. Harlequin Rasboras

Ease: 9/10. One of the safest choices for this tank setup.

Harlequin Rasbora

A peaceful schooling fish. An ideal community fish. A great beginner fish

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• Scientific Name: Rasbora heteromorpha
• Origin: Southeast Asia
• Minimum tank size: 10 gallons
• Care Level: Easy
• Swimming Level: Upper/Middle
• Adult Size: 1.5 inches
• Water Temperature: 72 – 77 °F
• pH: 6 – 7.5
• Diet: Omnivore

Harlequin rasboras are hardy schooling fish that make a great addition to a molly fish community tank. These colorful fish have a rich orange body color with a bold black triangular marking on each side.

They enjoy similar water parameters to molly fish but will do best towards the lower end of the pH and water temperature range. Add a school of 8 or more to enjoy their beautiful schooling behavior.

13. Bristle Nose Pleco

Ease: 9/10. One of the safest choices for this tank setup.

Bristlenose Pleco

The Bristlenose Pleco is a smaller Pleco that does a great job of eating algae. Peaceful and gets along with most fish

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• Scientific Name: Ancistrus sp.
• Origin: South America
• Minimum tank size: 30 gallons
• Care Level: Easy
• Swimming Level: Bottom
• Adult Size: 6 inches
• Water Temperature: 72 – 82 °F
• pH: 6.5 – 7
• Diet: Omnivore

Are you looking for a unique bottom dweller to add to your molly fish tank? Look no further than the weird and wonderful bristle nose pleco! These small armored catfish spend their time hanging out at the bottom of the tank.

They graze on algae and driftwood, and won’t bother your mollies, although you should only keep one pleco in the tank to avoid any fighting. Just make sure you pick up a bristle nose pleco rather than a larger species.

14. Swordtails

Ease: 9/10. One of the safest choices for this tank setup.

• Scientific Name: Xiphophorus hellerii
• Origin: Mexico & Central America
• Minimum tank size: 20 gallons
• Care Level: Easy
• Swimming Level: Middle/upper
• Adult Size: 4 inches
• Water Temperature: 64 -82 °F
• pH: 7 – 8.3
• Diet: Omnivore

The swordtail is yet another great livebearer for freshwater tanks. They are extremely peaceful and come in an exciting array of different colors and breeds. Swordtails are a little smaller than mollies and the males have a long, distinctive tail which is where they get their name.

These hardy fish are very easy to care for and won’t interbreed with your mollies. Swordtails enjoy very similar water parameters too, so you won’t need to worry about the two being comfortable in the same tank.

15. Tiger Barbs

Ease: 9/10. One of the safest choices for this tank setup.

• Scientific Name: Puntius tetrazona
• Origin: Southeast Asia
• Minimum tank size: 30 gallons
• Care Level: Easy
• Swimming Level: Middle
• Adult Size: 3 inches
• Water Temperature: 74 – 79 °F
• pH: 6 – 7
• Diet: Omnivore

Tiger barbs have a reputation for being a little mean towards other fish, but fortunately, mollies are tough and hardy, so they can handle themselves just fine. However, make sure to keep your tiger barbs in a school of at least 6 (preferably more) to prevent any aggression.

Community Aquarium Setup

Are you ready to set up your own molly fish community tank? Let’s take a look at what you will need!

Aquarium Size

Molly fish are often kept in tanks as small as 15 gallons, although I would recommend starting at 30 gallons for a small community setup. A 55-gallon tank would be a better option if you want to have a few different fish species in schools.

Heating

Molly fish require a heater in most homes. If you live in a warm area, you is able to keep molly fish in an unheated aquarium with other fish species like white cloud minnows, swordtails, and zebra danios.

A reliable heater is a safer bet because it allows you to maintain a healthy, stable temperature for your fish. An electric thermometer with an alarm that sounds when the water gets too cool is very useful as a reminder if you’re going to be switching off your heater for the summer.

Filtration

Good filtration is the difference between a healthy vibrant tank and a toxic environment. Invest in good filtration if you want the best for the fish in your molly community tank.

A large sponge filter (or two) is a doable option for your molly community tank, but a hang-on back or canister filter is going to provide much better mechanical filtration in larger aquariums.

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Don’t be afraid to run two different filters in your community tank. Overfiltering is a great way to keep your water quality high, although you should take care to keep your water flow down to low or moderate levels.

Decorations and Substrate

Adding decorations and substrate is a great way to make your molly community tank a more interesting environment for your fish, and a more appealing display for you and your family.

You can let your creativity run wild when arranging your layout, or take a more natural approach to recreate the wild environment of your fish.

Whichever route you take, make sure you use fish-safe products that are designed for aquarium use. You can design a beautiful layout by using a combination of the following materials:

• Substrate: Sand, gravel, or aquarium soil
• Driftwood: Spiderwood, manzanita, etc.
• Rocks: Dragon stone, seiryu, lava rock, etc.
• Ornaments/decorations: Caves, sunken ships, castles, etc.

Live plants

Live plants make the difference between a good aquarium and a great aquarium. They might not be for everyone, but aquarium plants is remarkably easy to care for and provide some amazing benefits for your fish.

Start with the following species if you’re new to growing live plants:

• Java Fern – A low-maintenance epiphyte
• Amazon Sword – A large-leaved rosette plant
• Water Wisteria – A fast-growing stem plant

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Feeding your fish

Molly fish are very easy to feed, like most of the recommended tank mates in this post. They will thrive on a diet of high-quality prepared foods like flakes or pellets. Feed your fish once or twice a day, providing only enough food for them to finish in a minute or two.

Supplement your fish’s diet with occasional treats like frozen foods, baby brine shrimp, blood worms, and other insect larvae. It will improve their condition, and they’ll love it too!

Some fish have specialized diets, and the otocinclus catfish mentioned in this article is a good example.

These tiny catfish only eat algae, so they need to be kept in a mature, healthy aquarium with a good supply of natural algae. They can also be fed with vegetables like zucchini and other algae foods like wafers.

Where To Buy Aquarium Mates

All the fish in this list of tank mates for molly fish were selected to be easy to care for and easy to locate. You should have no trouble finding them at most pet stores, but consider buying from some of my recommended online dealers for a hassle-free online shopping experience! Flip Aquatics gets my full recommendation as they quarantine all their livestock.

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Mark’s Pick: Platies and swordtails. Same water parameter preferences, similar temperament, and they produce fry at similar rates. A livebearer-only community is the most natural and stable combination for mollies.

FAQs

Who Is This Setup Right For?

After years of setting up and advising on molly communities, the setups that worked best were always the ones built around water chemistry first, fish second. Mollies are not a fish you build a mixed tropical community around, they’re a fish you build a livebearer community around.

Good Fit If:

• You have hard, alkaline water, pH 7.5–8.5, that naturally suits mollies and other livebearers
• You want a livebearer community with platies, swordtails, or guppies
• You’re prepared for constant fry production and have a plan for the offspring
• You want an active, colorful freshwater community with minimal aggression

Avoid If:

• You keep discus, rams, or other soft-water species that need different parameters
• You have no plan for molly fry, they breed without any intervention and populations grow fast
• You want to mix mollies with cichlids, most cichlids will harass or eat them
• You have a tank with hard-to-maintain water chemistry, mollies need consistency

Final Thoughts

Molly fish are one of the most popular species in the aquarium hobby for a good reason. These fascinating and hardy pets get along great with many other fish species. Pick tank mates from this list for your own community aquarium and enjoy everything these fish have to offer!

Do you keep molly fish in a community tank? Tell us about your favorite tank mates in the comments below!

📘 Want to learn more? This article is part of our complete Freshwater Fish Guide. Your ultimate resource for freshwater species, care tips, tank setup, and more.

Table of Contents

• Frequently Asked Questions
• A Quick Overview On The Electric Blue Acara
• Classification
• What Is Are They?
• Origin and Habitat
• Appearance
• Care
• Community Tank Mates
• Breeding
• Common Health Problems
• Final Thoughts

Electric blue acaras are one of the best cichlids for community tanks, but that does not mean they are easy. They still dig, still get territorial during breeding, and still need clean water to keep that color. I have seen too many people treat them as a beginner fish and then wonder why their acara looks washed out and hides all day. Get the setup right and this fish is incredible. Get it wrong and you will never see what it is capable of. The cichlid that finally made peaceful and stunning work in the same sentence.

The cichlid that finally made ‘peaceful’ and ‘stunning’ work in the same sentence.

What Most Care Guides Get Wrong About Electric Blue Acara

The misconception I encounter most with electric blue acaras is that they’re as aggressive as other acaras. They’re not. The standard blue acara (Andinoacara pulcher) is a noticeably more assertive fish. The electric blue variant has been selectively bred for color, and in that process, much of the aggression has been bred out. I’ve kept them successfully in community tanks with tetras and corydoras, which would be risky with a standard blue acara. The second myth is that they’re a naturally occurring species. They’re a line-bred color morph, and that selective breeding also means they is slightly less hardy than their wild-type cousins.

A Quick Overview On The Electric Blue Acara

Classification

What Is Are They?

The electric blue acara is not a naturally occurring fish. This is a hybrid mainly derived from the naturally occurring blue acara, Andinoacara pulcher; it is believed that they were mixed with blue ram cichlids (Mikrogeophagus ramirezi) at some point as well. This means that the electric blue acara cannot be found in nature and has been bred for its color expression within the aquarium hobby.

While a hybrid, the electric blue acara is still regarded as the Andinoacara pulcher species. They are members of the Cichlidae family and a type of South American cichlid.

In the aquarium hobby, the electric blue acara is a favorite cichlid to keep due to its bright coloration, hardiness, conforming temperament, and easy breeding. Unlike other similar South American cichlids that are mouth brooders, the electric blue acara is an egg layer that displays excellent parental care.

When shopping for your electric blue acara, make sure to confirm whether it is a hybrid or the parent species. Some fish stores may label this species as blue acara or simply acara, which is confusing.

Origin and Habitat

The electric blue acara (video source) may not occur in the wild, but its closest relative, the blue acara, does. The blue acara originates from South America, mainly throughout parts of mainland Venezuela and off the coast in Trinidad and Tobago. They have also been documented in several other countries as nonnatives, but little documentation of their range exists.

In these countries, the blue acara is found in a variety of ecosystems. These conditions range from murky, standstill waters to clear and running rivers. As a South American cichlid, the blue acara prefers softer and more acidic water parameters.

Appearance

What makes the electric blue acara so appealing to hobbyists is its colors. These fish are a flash of brilliant light in the aquarium with their bright blue bodies!

The electric blue acara was hybridized from a series of overly bright and colorful blue acara as well as blue rams. This led to their almost-metallic pale blue body color; some fish may have underlying hints of yellow or orange. Lower-grade acaras will even have patches of blue missing, revealing sections of black and grey.

Electric blue acaras have relatively large fins with respect to their body size. Mature males have a longer and more pointed dorsal fin while females have smaller fins overall. They can both display a yellow or orange margin on the top of the dorsal fin.

This difference in size is not always a tried and true method to tell male and female fish apart, though, especially if they’re still juveniles. As we’ll see, male and female pairs will need to form on their own in most scenarios.

Care

The electric blue acara is a hardy fish without many needs. Remember, blue acaras is found in a variety of environmental conditions, which means that these freshwater fish can also adapt to most aquarium conditions.

All in all, the electric blue acara has very basic cichlid care requirements.

Aquarium Setup

While you will have a perfect aquarium setup in mind for your new electric blue acara, your fish will have other plans. Like other cichlids, electric blues will rearrange the tank to how they like it, especially during spawning periods.

Electric blue acaras are relatively large fish that enjoy their swimming space. They mainly stay towards the bottom of the tank but will venture into the upper middle portions at times.

The best electric blue acara tank will have a minimal design with open space that accents the natural colors and behaviors of the fish. This includes a sand substrate along with driftwood or rock for decoration.

Electric blue acaras can successfully be kept with live plants, but only species that mind being uprooted from time to time. Because of this, hobbyists only keep floating plants with their cichlids.

Good live plants for electric blue acaras include:

• Anubias spp.
• Java fern (Leptochilus pteropus)
• Java moss (Vesicularia dubyana)
• Water sprite (Ceratopteris thalictroides)
• Hornwort (Ceratophyllum demersum)
• Duckweed (Lemna spp.)

These fish don’t need a lot of plant coverage, but a backdrop of green will especially make their colors pop out. Floating plants is helpful for dimming lighting conditions and making fish feel more like in their natural habitat.

Otherwise, electric blues can absolutely be kept in a community tank. I’d actually call them one of the most community-friendly cichlids in the hobby setting as long as small fish species are able to find protection in size, a school, or in decorations.

Tank Size

There are many ways to set up a tank with the electric blue acara in mind. Hobbyists use this fish species as the showpiece of the display, with all other species being catered towards them. Other hobbyists keep only electric blue acaras in their tanks and let them breed.

The bare minimum tank size for an electric blue breeding tank is 40 gallons. This allows for the male and female fish as well as the fry until they are big enough to stop receiving parental care. If planning on keeping a pair of electric blue acaras in a community tank with other species, then at least 55 gallons is recommended with a larger tank size being much more preferred.

Electric blue acara are active swimmers that need a lot of open space to enjoy. As a cichlid species, they can also be territorial, especially the males during spawning times. To help prevent any possible aggression from this otherwise peaceful fish, a larger tank will allow for more space between tank mates.

Water Parameters

The electric blue acara is a hardy fish that adapts to most aquarium water conditions. They are regarded as a beginner cichlid species, forgiving imperfections and wavering water parameters. That being said, they cannot tolerate ammonia or nitrite and breeding will demand more specific parameters.

To keep your electric blue as happy and healthy as possible, imitate the conditions found in the blue acara’s natural habitat in South America. This means soft, acidic water with water hardness between 2 and 10 KH and pH between 6.0 to 7.0. They are tropical fish and need a tropical water temperature between 74° F to 82° F.

Tank Maintenance

A weekly or biweekly 15 to 25% water change should be performed to keep nitrates low and to keep water quality up. Live plants will help keep nitrate levels from rising, but the rest will need to be manually removed. Most tanks do well with under 20 ppm nitrate.

At the same time as the water change, the substrate should be vacuumed to remove uneaten food and other wastes that will have accumulated. Because these are bigger fish, they’ll eat bigger foods that cause a lot more nutrients to enter the water column if left to rot.

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Filtration and other aquarium equipment should also be cleaned every few months depending on waste and algae buildup.

Filtration and Aeration

Electric blue acaras do well with a hang on the back or canister filter. They do not have any special filtration needs other than regular maintenance.

This filter should be rated for at least 2x the size of the tank as these are relatively big fish. Electric blue acaras do best in a slow to medium flow, though they can adapt to higher water currents as long as there are areas of lower flow throughout the aquarium. Also, note that a higher flow can upset a sand substrate in addition to the disruption caused by your fish.

Additional aeration is not necessary but an air stone is used to help circulate lower portions of the tank and to add aesthetic.

Lighting

Though these colorful fish look best under high lighting, they prefer low to medium light settings. Because hobbyists don’t keep light-demanding plant species with electric blue acaras, there is no recommended light setup; these fish will thrive under a fluorescent or LED light fixture.

If the light fixture is too intense, then floating plants and other aquarium decorations is used to diffuse bright areas. A low water flow in addition to high lighting can fuel algae growth.

Aquatic Plants and Decorations

As mentioned before, electric blue acara is kept with a variety of live plants. The problem is that these fish regularly uproot and disturb their surroundings, so the species of plants kept must be able to tolerate some rough handling.

Again, some of the best species include Anubias, Java fern, and hornwort. Though hobbyists may try to tie or glue these plants down, your fish will rearrange the tank to its liking eventually.

The same is said about the aquarium decorations used. Most cichlid enthusiasts keep their tanks simple with rocks, like Texas holey rock, ceramic flower pots, and driftwood. Electric blues will likely claim a piece of this real estate for themselves and guard it against other tank mates, though in a passive manner. During spawning times, electric blue acara will become noticeably more aggressive and territorial.

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Substrate

Almost all cichlids love to burrow in the sand. Some even create breeding pits where they spawn, including the electric blue acara.

These aquarium fish will do best on a sandy substrate where they are free to change their surroundings based on their own preferences. This can certainly become messy at times and leave the controlling aquascaper frustrated. However, gravel can frustrate the fish and even injure them.

Is the Electric Blue Acara Right for You?

Before you commit to this species, here’s an honest assessment of whether it fits your setup and experience level.

• One of the best cichlids for community tanks. Their mild temperament makes them compatible with a wide range of peaceful to semi-aggressive species.
• Stunning color that rivals saltwater fish. The iridescent blue coloration is genuinely breathtaking under good lighting.
• Perfect for keepers who want a cichlid without the drama. If you like the personality of cichlids but don’t want to manage aggression, this is your fish.
• Needs a 30-gallon minimum. They reach about 6-7 inches, so they need more space than most dwarf cichlids.
• Not the hardiest cichlid available. Their selective breeding means they can be slightly more sensitive to water quality swings than wild-type species.
• Excellent for planted tanks. Unlike many cichlids, they leave plants alone and look spectacular against green backgrounds.

Food and Diet

One of the best things about electric blue acara is that they eat anything you offer them! These fish are not picky and are a joy to watch eat. That being said, they need a high-quality diet to keep their colors shining brightest.

Electric blues will appreciate a variety of live, freeze-dried, and frozen foods. They are larger fish that need to be fed several times throughout the day. To help keep costs down, a high-quality fish food flake or pellet may be given regularly. Brine shrimp, mysis shrimp, bloodworms, earthworms, and even fresh pieces of mollusk and fish may be given as a treat.

A poor diet will not result in the best colors and may affect the success of broods and the spawning process.

Community Tank Mates

Electric blue acaras are a favorite cichlid due to their passive demeanor. They is kept with an assortment of tank mates, both bigger and smaller, more active and less active.

The best electric blue acara community tank mates include:

• Larger tetras
• Barbs
• Corydoras
• Loaches
• Plecos

They have even been safely kept with larger invertebrates, including dwarf crayfish and nerite snails.

If you’re looking for a cichlid-tank setup, then here are the best compatible cichlid species for your electric blue acara:

• Severums (Heros severus)
• Geophagus spp.
• Angelfish (Pterophyllum scalare)
• Apistograma spp.
• Rams (Mikrogeophagus ramirezi)

Poor Tank Mates

While the electric blue acara is one of the most adaptable cichlid tank mates, they’re not right for every home aquarium setup. Poor tank mates are ones that can easily fit in an electric blue’s mouth or ones that are overly aggressive or that try to fight back!

In addition, small invertebrates, like dwarf shrimp and snails, will also be seen as food for your electric blue acara.

Breeding

Breeding electric blue acara is fun and easy. Unlike other similar cichlids, the electric blue acara is an egg layer and not a mouthbrooder. These fish still display some excellent parenting, though! Check out the video below from Uri Shasha.

The most challenging part about breeding electric blues is getting a good breeding pair. As mentioned before, it is difficult to tell the males apart from the females. Males are larger with more elongated and pointed dorsal fins, while females are smaller. Even as adults, these physical differences is hard to see.

Luckily, electric blue acaras are monogamous fish that mate for life. They become sexually mature when they are 1 year old and about 4 inches.

To get a breeding pair, it’s recommended to purchase a small group of juveniles and allow them to pair off on their own. Once mature, the best pair may be picked. These fish may then be bred in the main display aquarium or in a breeding tank. A 20-gallon breeding tank will allow for more control and overall success in keeping fry alive.

In either case, the water temperature should be set to 77° F with a relatively neutral pH and slightly soft water. When ready, the female will lay her eggs on flat rocks or other accessible surfaces throughout the aquarium. One clutch includes about 100 to 200 eggs. The male will quickly fertilize them once laid.

Over the course of the next two to three days, the parents will protect the eggs. It’s possible that they will create a pit in the substrate where they will move the fry once hatched. This can cause a lot of disruption to the substrate and aquascaping. During this time, males will become especially aggressive towards other tank mates, though won’t injure or kill them.

After these few days, the eggs will hatch. The parents may move the fry to the pit or leave them where they are. The parents will continue to deliver care until the fry are fully free-swimming. Then, the parent electric blues will deliver food to the fry, so small foods, like baby brine shrimp, should be supplemented. At this point, the fry or the parents may be removed from the tank to increase survival chances. This is especially recommended if spawning these fish in the main display.

Over the next two months, the baby fish will continue to develop. They should continue to be given small fry food, but can eventually be fed crushed fish flakes. Once big enough, the baby electric blue acaras is moved to the display aquarium or given to another hobbyist.

The parent electric blues will be ready to mate again in a matter of weeks. Once they have started, they are likely to continue as long as water quality and other tank conditions are met.

Common Health Problems

Electric blue acaras are hardier than most fish. Because they’re hybrids, they exist only in the aquarium hobby and have been exposed to the most common health problems. Still, these fish are susceptible to freshwater ich and skin flukes. Luckily, these problems is easily treated and easily avoided.

When purchasing an electric blue acara, make sure that its colors are bright and its behaviors are normal. These fish should be active and colorful. Always ask the store representative to watch them eat; if there is any refusal, the fish is most likely sick or stressed.

As always, it’s recommended to quarantine new fish for at least three weeks before adding them to a new system.

What It Is Actually Like Living With Electric Blue Acara

This is the part no other care guide gives you. Forget water parameters for a minute. Here is what it is actually like to share your tank with this species.

They greet you at the glass. EBAs are personable fish that learn your routine. They come to the front of the tank when you walk in the room, and some will eat from your hand with patience.

Breeding is almost inevitable. If you have a male and female, they will breed. EBAs are prolific spawners that lay eggs on flat surfaces. The parents guard the eggs and fry aggressively, which changes the entire dynamic of a community tank.

They are surprisingly compatible. I have kept EBAs with angelfish, rainbowfish, and even discus without issues. Their low-aggression profile makes them one of the most versatile cichlids in the hobby.

Color intensity fluctuates. EBAs can look electric blue one minute and pale the next. Mood, lighting, diet, and water quality all affect their coloration in real time. Do not panic if they look washed out after a water change. It is temporary.

How the Electric Blue Acara Compares to Similar Species

The natural comparison is the standard blue acara (Andinoacara pulcher). The standard version is hardier, slightly more aggressive, and available wild-caught. Electric blue acaras are calmer and more colorful but is less robust due to selective breeding. If you want a community-friendly cichlid, the electric blue is the better choice. If you want maximum hardiness and don’t mind some territorial behavior, the standard blue acara is more forgiving.

The German blue ram is another comparison for keepers wanting a colorful, peaceful cichlid. Rams are smaller (2-3 inches vs. 6-7 inches for the electric blue acara) and significantly more temperature-sensitive, needing 82°F+ to thrive. Electric blue acaras are comfortable in the standard tropical range of 72-82°F, making them easier to keep in mixed community tanks. For most keepers, the electric blue acara is the more practical choice. Similar beauty, less demanding care requirements, and a longer expected lifespan.

Final Thoughts

An electric blue acara in the wrong setup is just a grey fish hiding behind a rock.

Electric blue acaras are an extremely popular hybrid cichlid. These beautiful fish are vibrant in coloration and behavior and are some of the easiest cichlids to breed. Electric blues are large fish, so they need to be given plenty of space, especially if planning to keep a pair with other tank mates. However, they is kept in a variety of tank setups and will accommodate the demeanors of other fish.

South American Cichlid Species Directory

This article is part of our South American Cichlids: Complete A-Z Species Directory. Visit the hub page to explore care guides for all 32 South American cichlid species we cover.

The Comet Goldfish is not a beginner fish. It is a cold-water species that produces enormous waste, needs real filtration, and outgrows most tanks within a year. I have kept goldfish in ponds and large tanks for over 25 years. Here is the honest care guide most people need before buying one.

A goldfish in a bowl is not thriving. It is slowly suffocating.

Goldfish live 10 to 15 years, sometimes longer. This is a decade-long commitment to large water volumes, heavy filtration, and consistent maintenance.

A goldfish kept properly is more impressive than most tropical fish. The problem is almost nobody keeps them properly.

Table of Contents

• Key Takeaways
• What Most Care Guides Get Wrong
• Comet Goldfish Overview
• Classification
• What Is A Comet Goldfish?
• Origin and Habitat
• Appearance
• Care Requirements
• Diet
• Breeding
• Common Health Problems
• Final Thoughts
• Is the Comet Goldfish Right for You?
• Species Comparison
• The Reality of Keeping Comet Goldfish

What Most Care Guides Get Wrong About Comet Goldfish

Want a pond fish? Get comets or shubunkins. Want an indoor aquarium goldfish? Get fancies and plan for a 40-gallon minimum. Want a low-maintenance pet? Get a betta instead.

Most care sheets list the minimum tank size for Comet Goldfish and call it a day. But a minimum is just that. In my experience, giving them more room changes their behavior completely. You see more natural movement, less stress, and fewer aggression issues. Another thing guides gloss over is temperament. Comet Goldfish are often described with a single label, but their behavior shifts depending on tank size, tank mates, and territory. You need to plan for the worst-case scenario, not the best. Group size is another area where most guides fall short. Saying ‘keep them in groups’ is not enough. The difference between keeping 3 and keeping 8 or more is night and day when it comes to coloration, confidence, and natural behavior.

Comet Goldfish Overview

Classification

What Is A Comet Goldfish?

Most people have owned a goldfish at one point or another in their lives. But did you know that there are many different types of goldfish all with their own unique traits and characteristics?

The comet goldfish is a common breed of goldfish, scientifically known as Carassius auratus. These fish are very similar to the main breed of goldfish, the common goldfish. While these two fish are the same species, there are a few differences between them and other goldfish. As we’ll see, the main difference lies in the shape of their tail fin.

Origin and Habitat

Want a pond fish? Get comets or shubunkins. Want an indoor aquarium goldfish? Get fancies and plan for a 40-gallon minimum. Want a low-maintenance pet? Get a betta instead.

Goldfish have been domesticated for hundreds of years for their colors and symbolism. These fish were and still are a sign of wealth and prosperity, though many hobbyists adore them for their extreme hardiness and variety of breeds.

The first goldfish were domesticated from crucian carp. These carp originated in China from cold and shallow lakes and ponds. Crucian carp feature dusky brown and yellow coloration. Over time, the undertones of yellow and orange were selectively bred until arriving at the intense coloration of the common goldfish today.

However, the breeding didn’t stop there. There are estimated to be well over 100 breeds of goldfish, with the comet being one of the most closely related to the common goldfish.

Comet goldfish and common goldfish do not naturally exist in the wild. In fact, no breed of goldfish exists in the wild. Sadly, many people are unaware of goldfish’s true needs and release them into nearby streams and rivers. Many of these fish don’t survive, but some do. This makes them an invasive species that will impact ecosystems on a large scale¹. 

Appearance

The comet goldfish is one of the more basic-looking breeds of goldfish. There are a few differences between this breed and the common breed. The biggest difference lies in their fins.

Comet goldfish have long and flowing fins that resemble the tail of an astronomical comet. This is in comparison to the common goldfish’s short and triangular fins that follow close behind. The biggest difference between these two fins is that comets have a deeply forked tail fin while common’s have a slight indent in the middle.

For the most part, common goldfish only come in typical goldfish-orange coloration. Comets offer more variety with orange, yellow, red, and white color patterns. 

How Big Do They Get?

One of the most important factors to consider when choosing a breed of goldfish is its potential size. Common goldfish can easily surpass a foot in length, though most stay about 10 inches on average.

Because of their long, flowing fins, comet goldfish size is going to be slightly larger, reaching mature lengths of 12 inches. It should also be said that while these fish grow to be long, they can also grow to be pretty chunky too!

Do They Stop Growing?

It’s long been said that fish will only grow to be the size of the tank that they’re given.

Or maybe you’ve heard that fish will have externally stunted growth in small tanks, but that their organs keep growing on the inside.

While this area of fish biology has been little studied, it is true that both these statements are false. The majority of fish, including goldfish, are indeterminate growers that continue to grow with age as long as environmental conditions allow. Though it might seem like your fish has comfortably grown into its tank, it’s actually being stunted due to other factors, including limited space, poor water quality, and in diet. However, its organs will grow in relationship to its body.

Color Variations

Not all goldfish are gold. In fact, the comet goldfish comes in many different colors besides the traditional copper tone of the common breed. These fish is orange or yellow and have red and white color patterns. Some of these color combinations have been specifically bred with design in mind.

These designer comet goldfish include:

Sarasa comet goldfish. This variety has a white body with multiple solid bright red spots. This red coloration is on the dorsal portions of the fish but can extend to the underbelly as well.

Tancho single-tail comet goldfish. The Tancho coloration is simple yet effective. These fish have a bright red cap on their head while the rest of the body stays iridescent white. This cap may be irregular in shape, sometimes splitting in half.

Care Requirements

Want a pond fish? Get comets or shubunkins. Want an indoor aquarium goldfish? Get fancies and plan for a 40-gallon minimum. Want a low-maintenance pet? Get a betta instead.

Goldfish are an oxymoron. They are an easy fish species to keep, but their care requirements is surprisingly demanding. While comet goldfish are very hardy fish that can survive less-than-perfect water conditions, they require a lot of upkeep and maintenance to keep them happy and healthy.

Aquarium Setup

Goldfish setups are simple by design. These fish do best with tons of open swimming space, little to no decorations, and strong filtration. No matter what though, these fish cannot live in a goldfish bowl!

Comet goldfish are inexpensive fish that are won at carnivals and fairs. They are sometimes even sold as feeder fish for other larger predatory species. Because of their inexpensive price and oftentimes small holding tanks, unknowing goldfish owners think that they don’t need an elaborate setup. While this is true, there are some conditions that need to be met.

A good comet goldfish tank will be a large tank with an appropriate substrate, good water flow and aeration, correct water temperatures, and appropriate tank mates. Comet fish can also be kept in outdoor ponds as they hibernate over the cold months.

Some goldfish enthusiasts keep live plants with their comets. Plants add many benefits to the home aquarium and are essential for keeping a natural environment in pond settings. However, goldfish love to eat and uproot plants, which can add additional waste to the system. Hardy and fast-growing species, like Anacharis and hornwort (Ceratophyllum demersum), is successfully kept in a goldfish aquarium.

Tank Size

Sadly, many goldfish are kept in improper tank sizes. These are large and active freshwater fish that create a lot of waste. They need space to move around and water volume to help keep ammonia and nitrite levels down.

The minimum tank size recommended for one comet goldfish is a 55 gallon tank. This might seem like a lot, especially when the fish is only a few inches big. However, comet goldfish can grow to over 10 inches in the first couple of years of their life. Too many hobbyists purchase goldfish with the intention of getting a larger aquarium or building a pond. Many times, these plans fall through and the fish is left in too small of a tank (video source).

In order to keep another comet goldfish, a 75 gallon tank is needed. In general, every additional fish requires another 40 gallons of water. This is why these fish will do best in a large pond setting, though it is possible to keep multiple comet goldfish long-term in the home aquarium.

Water Parameters

It’s important to goldfish aren’t tropical fish like many of the other species available in the aquarium hobby. They originate from cold waters and need to be kept in cooler conditions in the home aquarium setting. For experienced keepers, this means buying an aquarium chiller to help keep the water temperature down.

The ideal water temperature range for comet goldfish is between 60ºF and 72ºF. Experienced keepers keep their comet goldfish tank above or below these values, but overly hot temperatures can lead to stress while cooler temperatures can lead to hibernation. Ambient room temperature is often enough to keep a goldfish aquarium heated, but extra stability is achieved through a low-range heater.

On top of colder water temperatures, comet goldfish care relies heavily on maintaining ammonia and nitrite levels. These fish create a ton of waste through their diet and fast metabolism. Most oversized filtration can keep up with processing fish waste, but regular tank maintenance and weekly or daily water changes are also needed; most hobbyists perform upwards of 25% water changes at any given time.

Lighting

Comet goldfish do not require special lighting. Because they are not commonly kept with live plants, there is no need for high-tech equipment. Instead, comet goldfish can live under LED or fluorescent settings.

There is a chance that your goldfish will change colors based on the intensity of the lighting; a darker light will cause your fish to become darker and vice versa.

Filtration and Aeration

One of the most important aspects of keeping comet goldfish is picking the right filtration. These are big fish with fast metabolisms that create a lot of waste. It is recommended to use filtration that is rated for at least 4x the size of the aquarium, with bigger always being better.

Since hang-on-the-back filtration can become too big for the side of the tank, many goldfish keepers use a canister filter. Canister filters are also advantageous as the return nozzles is pointed downwards to help pick up and remove waste from the bottom of the tank. Multiple hang on the back filters or canister filters is used for adequate filtration and circulation.

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To help supplement water flow, powerheads and air stones may also be added. Goldfish have adapted to waters with low dissolved oxygen levels, so air stones aren’t necessary for increasing oxygen. Instead, they is efficient at keeping fish waste from resting at the bottom of the aquarium.

Substrate

Goldfish do best without any substrate in a bare-bottom aquarium setup. In fact, having a substrate can create more work for the owner.

All goldfish, including comet fish, love to dig in and around gravel and sand substrate. They uproot plants, move decorations, and kick up detritus that gets stuck on the bottom. This can become messy over time and lead to problems with water quality. In addition, a bare bottom makes aquarium vacuuming and waste removal much easier, which is essential for keeping a goldfish aquarium clean.

That being said, goldfish have successfully been kept on both gravel and sand substrates. Extra care and maintenance will be needed to keep waste from entering the water column.

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Tank Mates

Once you choose to set up a goldfish tank, there is little you can do to have any other fish besides goldfish. This is mainly because of differences in preferred water temperature, but also because of differing temperaments and behaviors as well as bioload. Goldfish need to be kept with other large and active cold water species, and not many fish meet their criteria or behave as good tank mates.

The best tank mates for comet goldfish are other single-tail breeds, namely other comets and common goldfish, in addition to koi fish. Unfortunately, these pond fish must be kept with like-breeds and cannot be mixed with fancy varieties. Fancy goldfish are too slow and delicate to compete with much more active comets.

Experienced keepers have had success keeping zebra danios (Danio rerio) and dojo loaches (Misgurnus anguillicaudatus) with their comets, but we do not recommend this setup for under 100 gallons.

Diet

Goldfish are some of the least picky fish when it comes to feeding them; so much so that they might try to eat your finger!

Comet goldfish are omnivores, which means that they need meat- and plant-based foods. They largely accept most aquarium foods, including live, frozen, and freeze-dried brine shrimp, earthworms, and bloodworms. They will also gladly munch on blanched vegetables, including lettuce, cucumber, and zucchini. Experienced keepers also cultivate easy-to-grow live plants, like Anacharis, to feed their goldfish.

To help keep costs low, comet goldfish is given high-quality goldfish pellets or flakes.

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Comet goldfish will eat as much food as you give them. This means that food should be given in moderation and any leftovers that happen to evade your fish should be removed to keep waste levels low.

Breeding

Though easy fish to keep, breeding comet goldfish is difficult and can only be achieved in a large pond setting. There isn’t a huge market for regular comet goldfish in the aquarium trade, so giving fry away can also be challenging.

Because breeding goldfish in an aquarium setting requires very large systems, we will only focus on spawning comet fish in a pond setting. Spawning naturally occurs during late spring/early summer when the water temperature starts to rise. This is replicated in the home aquarium by using a heater.

First, establish a male and female pair. Females are rounder and more robust than streamlined males. Female comets may also develop protruding anal vents during spawning periods while males may develop white tubercles on the gill covers. When ready to mate, males will chase the female in hopes that she will drop her eggs to be fertilized. Because of this aggressive courtship, at least 2 to 3 females should be kept per every male.

When ready, the female will lay her eggs., this is near vegetation, a spawning mop, or another safe structure. The male will fertilize them and they will hatch after a few days. During this time, the parents and other goldfish are likely to eat the eggs. For better success, remove the fertilized eggs and move them to a separate system.

When the eggs hatch, the fry will stay toward the substrate as they feed off their egg yolk. As the egg yolk runs out, they will become free-swimming and start to search for food. At this point, they may be offered baby brine shrimp, crushed-up pellets and flakes, and other microscopic foods.

Goldfish fry grow fast, so be prepared to transfer them to their final home within several weeks!

Common Health Problems

Like all aquarium fish, comet goldfish are susceptible to common fish diseases like ich, velvet, and fin rot. Because comets have elongated fins, they can easily develop fin rot if water quality is poor.

There are a few other problems that are unique to goldfish, though.

Two of the main health problems with goldfish are ammonia poisoning and nitrite poisoning. Both of these conditions are a result of poor water quality and are easily avoided. However, poor water quality can also lead to swim bladder disease and dropsy, which is nearly impossible to treat.

A healthy goldfish always starts with good water quality. Make sure to quarantine new additions for at least 4 weeks and check your tank daily for any changes in appearance or behavior.

ASD Difficulty Rating: Tier 2 – Intermediate — Comet goldfish grow large, produce heavy waste, and live 10–15 years. Simple in concept, demanding in practice.

Hard Rule: Comet goldfish grow to 12 inches (30 cm) and are best kept in ponds. Standard aquariums stunt their growth, compromise their health, and shorten their lives to a fraction of their potential.

Is the Comet Goldfish Right for You?

Good Fit If:

• You have an outdoor pond or a 125+ gallon (474 L) aquarium for a long-term indoor setup
• You want an active, fast-swimming goldfish with a classic look
• You can commit to the filtration demands of a heavy bio-load fish
• You are comfortable with cooler water (60–70°F / 16–21°C) and no tropical fish

Avoid If:

• Your tank is under 75 gallons (284 L) – even that is only appropriate for juveniles
• You keep tropical species that need 78°F+ – comet goldfish prefer significantly cooler water
• You want a fish that stays small and manageable in a standard community tank
• You are not prepared for the long-term commitment of a fish that lives 10–15 years

Final Thoughts

Comet goldfish aren’t the showiest of all goldfish varieties, but they’re more exciting than the common goldfish. That being said, these are still huge fish that need a lot of space and good tank maintenance to keep them from developing health issues. Due to their size and bioload, they’re best in a large aquarium system or an outdoor pond.