Author: Mark Valderrama

Goldfish lifespan is one of those topics where the truth surprises almost everyone. Most people think goldfish are disposable pets that live a year or two, but properly kept goldfish regularly reach 10-15 years, and well-documented cases of 20+ year goldfish exist. I’ve seen what happens when goldfish are kept in appropriate conditions versus a tiny bowl — the difference in longevity is dramatic, and it all comes down to a handful of key factors.

The appeal of goldfish as pets is undeniable. They’re cute, active, and beautiful, on top of being relatively easy to care for.

Yet, despite this, something you’ll commonly hear about goldfish is that they don’t live very long. And unfortunately, that’s become true for most goldfish in captivity… but not for the reasons you might believe.

You see, it’s not that goldfish have inherently short lifespans. It’s that most people, especially those with insufficient fishkeeping knowledge/experience, don’t know what it takes to keep a goldfish alive for its true average lifespan.

So the question, how long do goldfish live, doesn’t have a straight answer. It all depends on how well they’re being brought up. Find out more below!

How Long Do Goldfish Live?

Assuming that the goldfish is healthy and treated with care, its life expectancy can go up to 15-20 years¹.

There are even records of some slim-bodied goldfish, like the feeder or common goldfish and comet goldfish, living up to 40 years in an outdoor pond, where the natural habitat of a goldfish is most closely mimicked.

Meanwhile, fancy goldfish lifespan generally ranges from 7-12 years. This is because compared to slim-bodied goldfish, they are much frailer. Their biological processes are also much easier to disrupt due to their organs being packed into a small, squat, round body.

Even the bubble eye, which makes certain species like the black moor so popular, can be a cause of lower life expectancy. In general, slim bodied goldfish can live longer than fancy ones.

Lifespan of Different Goldfish Types

Wondering how long do goldfish live? Here are the average goldfish lifespans of the most commonly sought types of goldfish:

Why Do Goldfish Die So Easily?

If you’ve been paying attention, you’ve figured out by now that the expected lifespan of your goldfish actually exceeds that of your other seemingly smarter and stronger house pets, like your dog or cat.

Yet, it’s more and more common to see that goldfish kept as pets don’t make it past 5 years of life. And this leaves a lot of confused first-time goldfish owners asking why their goldfish died so soon and how they can ensure a longer lifespan for their other goldfish.

So, a lot of it comes down to the care and living conditions of the goldfish.

If you can ensure healthy living conditions and tank or pond water quality for your goldfish, you can expect them to live out their expected lifespan of 15-20 years.

However, for goldfish cooped up in a little bowl or small tank, kept in unclean water containing significant amounts of waste, or not given a varied diet, the average life expectancy is 2-5 years.

Whoa, that’s a lot of information.

But it’s not even the start.

Wondering where you went wrong? Find out below.

How to Increase Goldfish Life Expectancy

Like all other beings on the planet, the lifespan of a goldfish is determined by how healthy it is. And ensuring that health is on you who are charged with their care. If you’re new to keeping these fish, don’t freak out. Here is how to extend that lifespan. With lots of care, maybe you to can raise a goldfish like Tish, who was the oldest goldfish. Tished lived to be 43 years! Let’s look at these 9 actionable tips before to get you started right!

1. Clean the Tank Regularly

Good water quality is of utmost importance if you want to facilitate a long goldfish lifespan. Especially considering how much waste they produce, it’s crucial to carry out frequent water changes to prevent toxicity. Always do your routine water changes and look into top notch filtration. You should regularly test your water to ensure you maintain lower nitrate levels and not have dangerous levels of ammonia or nitrite.

Additionally, get used to using your own intuition. Check how the water looks and how it smells. If you feel something is wrong, trust your gut and whip out your water testing kit. Prevention is always better than cure when it comes to the increasing life expectancy of fish.

2. Feed Your Goldfish a Healthy Diet

What most people think of as “fish food,” which are typically pellets and flakes, are actually more proprietary food than anything else.

So when we say “healthy diet,” we, of course, mean a varied, omnivorous diet. You want to give your goldfish a little bit of everything: pellets and flakes, some vegetables, live foods like worms and shrimp, and even fruit sometimes, to keep health problems at bay.

There is a comprehensive guide I have posted all about what do goldfish eat. Check out the guide. You will be blow away at what you can feed your goldfish!  

3. Don’t Overfeed Your Goldfish

If you’ve had your goldfish a while, you will have noticed by now that they will eat almost anything at any time. In fact, as long as it can fit in their mouth, these omnivorous creatures will attempt to swallow almost any object. All types of goldfish do this.

Yes, it’s cute watching a goldfish gobble up the food you lovingly give them. But you must not be tempted to overfeed them. It’s very easy for goldfish to get digestive health problems like bloating and constipation. It might even lead to swim bladder disease.

As a consequence, this will lead to a reduced goldfish lifespan.

4. Maintain the Water Temperature

If you want your fish to live long, you have to try to make sure that your goldfish tank mimics their natural habitat as closely as possible. An important component of this is maintaining the right water temperature.

For fancy goldfish, the optimum temperature is between 65° to 72°F, while for slim-bodied goldfish (like the common goldfish), the right temperature range is 60° to 72°F. Make sure you do proper research on the breed of goldfish you have.

If the temperature is too high, your goldfish will experience higher metabolism. Although this will cause them to grow bigger at a faster rate, it will shorten their lifespan. If you keep your goldfish in a pond and it freezes over in the winter, consider investing in a pond de-icer.

5. Give Your Goldfish the Space They Need

Film, TV, and children’s books have had us believing for years that a goldfish survive in a little fish bowls. This is absolutely incorrect and a sure-fire way to your goldfish to have a short lifespan.

The average lifespan of a goldfish in the wild is from 20-40 years, mainly because they have a lot of space to swim around in, less stress, and stable conditions.

So when forced to circle in one spot, e.g., in a bowl, a goldfish gets extremely stressed. And when that stress reaches its apex, your pet could die.

Not to mention, once again, goldfish produce a lot—and we really mean a lot—of waste. The smaller their tank, the more quickly and easily it will fill up with toxic goldfish waste and lead to your pet dying.

That’s why goldfish need a large aquarium size. One goldfish needs at least a 20 gallon fish tank to live in. And for every new goldfish you add, you must add another 10 gallons. So, don’t crowd your goldfish in small tanks.

6. Provide Adequate Filtration

This is, of course, true not only for goldfish but for any other pet fish. But given how much these guys love to poop, it’s absolutely essential to providing filtration for your goldfish tanks. A moderate filtration rate should be alright in goldfish tanks. Look to provide a high amount of biological filtration to manage the heavy bioload they add to your tank.

7. Choose Tank Mates Wisely

Not all fish should be kept with one another. This includes different goldfish species.

The bodies of fancy goldfish, as you may already know, are quite weak and slow compared to goldfish with slim bodies. As such, they should not be kept in the same tank because stronger fish almost always prey on weaker ones and will outcompete them for food.

8. Put Your Goldfish in a Pond

If you have very delicate fancy goldfish like pearlscales, ignore this bit—their genetics make it hard for them to survive in ponds.

On the other hand, if you have long goldfish of the slim-bodied variety, such as common goldfish, comets, and shubunkins, the best thing you can do to increase their lifespan is to put them in a freshwater pond.

In the wild, goldfish live in freshwater streams and ponds. Seasonal variations, plenty of sunlight, and naturally available sources of varied foods (e.g., plants, insects, larvae) all make an outdoor pond the best place for a goldfish to enjoy a longer lifespan.

Even some varieties of fancy goldfish, like the fantail variety, can be kept in a pond by fish keepers who are willing to put in the extra effort to create healthy conditions for them.

You might have to use implements such as a pond heater. Adjusting the pH is another concern, as well as preventing predators—like birds—from feasting on your goldfish (because, after all, being eaten is an effective way to shorten anyone’s lifespan).

9. Ensure Proper Bacteria Levels

One of the best ways to ensure a long and healthy life for your goldfish is to allow bacteria to thrive in their tank.

Why? Because bacteria keep goldfish waste in check.

Not only do goldfish love to eat and don’t know when to stop eating, they—quite predictably—are known to produce very large amounts of waste. And this waste contains toxins like nitrite and ammonia, which, when existing in large amounts in your goldfish tank, can damage your fish’s gills and even cause brain damage.

The result? Stress, a shortened lifespan, a sick fish, and maybe even death.

In freshwater bodies, the natural habitat of goldfish, the water conditions include naturally occurring bacteria that break down the goldfish’s waste. In a home aquarium, however, there are no bacteria. That’s why one of the ways of proper care of goldfish is introducing bacteria into their tank. This starts with a proper cycle.

Here’s how to do it.

How to Introduce Healthy Bacteria into Your Goldfish Tank

Let’s take you through all the necessary steps.

Step 1: Remove Chlorine from the Tank

One of the most common mistakes new goldfish owners make in fish care is bringing their goldfish home to an unprepared tank. Some people think it’s as easy as bringing the goldfish home and dumping it/them in the tank.

This is far from the truth. You need to prep your tank for your goldfish weeks and sometimes even months in advance, depending on the breed and amount of goldfish.

Start by ridding your goldfish’s new abode of chlorine. Use a conditioner to do this. Although chlorine is helpful in our drinking and bathing water, it inhibits bacteria growth in a fish tank.

Step 2: Allow Bacteria Into the Fish Tank

Once the chlorine is out, the bacteria will start pouring in pretty much all on its own. Not only from the air and the water itself but also from the plants and rocks you use to decorate your aquarium. Even commercially sold bacteria culture is easy to access these days. Fritz Turbo Start is my favorite bacteria for freshwater tanks.

My Pick For Freshwater Bacteria

Fritz Turbo Start 700 Freshwater

Fritz Turbo Start is known in the industry as the fastest acting nitrifying bacteria you can purchase. This 700 version is specialized for freshwater tank and has my highest recommendation

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But your work for your fish doesn’t end there.

Step 3: Drop Some Goldfish Food (Or ammonia) in the Tank

I know, it sounds a little silly right now; why put fish food in a fish tank with no fish?

Because it allows your bacteria to start doing their job.

Use fish flakes or pellets for this purpose. When this food disintegrates inside the tank, it will release ammonia. The bacteria, in turn, will consume this ammonia. In a few weeks, you will have a self-sustaining bacteria ecosystem inside your fish tank.

A more modern technique would be to use ammonia from a manufacturer like Dr. Tim’s Aquatics. This is what I’m used to doing for my fresh only systems. Once you have no ammonia and nitrites reading when you test your water, it’s time to add goldfish!

Step 4: Make Regular Water Checks

This is very important if you want to sustain healthy living conditions for your goldfish. Why not get yourself a water testing kit to regularly check water parameters? It’ll make your life a lot easier. Do your water changes to keep your nitrates down.

Frequently Asked Questions

1.   How long can a goldfish live in a bowl?

If you’re wondering how long can goldfish live in a bowl: not longer than 2 to 3 years. Goldfish bowls are not large enough to sustain a goldfish, which means leaving yours in a bowl will cause your goldfish to be underdeveloped and stressed.

Consider that a single goldfish requires at least 20 gallons of water to thrive before putting yours in a bowl.

2.   Why do goldfish die so easily?

The most common reasons for the lifespan of a goldfish being shortened are ammonia poisoning, excessive nitrate levels, and being kept in a tank that’s too small, among other reasons.

Therefore, you should make it a point to ensure that your goldfish’s tank water is clean and of good quality and provide them enough space to move around. Remember, one goldfish requires at least 20 gallons of water to thrive.

3.   How big can a goldfish get?

In captivity, slim-bodied goldfish can grow up to 10 inches. Fancy goldfish will typically grow to 6-8 inches. In the wild, these fish might grow up to 12-14 inches in length.

The largest ever recorded goldfish, owned by a man in the Netherlands, measured 18.7 inches.

4.   What kind of goldfish live the longest?

Species of goldfish that live the longest are the common goldfish, shubunkins, and comets. These slim-bodied goldfish types do require a lot of tank space compared to fancy goldfish but have been known to live longer than 10 years.

5.   What is the average lifespan of a pet goldfish?

On average, pet goldfish live 10 to 15 years. However, if if they aren’t kept in good housing conditions, they usually will live no longer than 5 years.

6.   How long can goldfish go without food?

Up to 2 weeks, depending on their health.

Closing Thoughts

Out of all the aquarium fish varieties you might choose to populate your home, goldfish are known to live the longest, with proper care. So, it really is a crying shame that these fish have developed a reputation for dying easily and quickly.

Don’t help to keep this idea alive. Whether in a tank or pond, treat your goldfish with love and care, and above all, humanely— and they will stay alive as long as they can to keep making you go awww at all of their little fish antics.

We hope the tips in our article have helped. We wish your goldfish a long and beautiful life!

📘 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.

Goldfish diet is something I’ve paid close attention to over the years, and the difference between a well-fed goldfish and one living on cheap flakes alone is genuinely striking — in body condition, color, and longevity. Goldfish are omnivores with a real appetite for plant matter, and feeding them a varied diet that reflects that goes a long way toward keeping them healthy for the long haul.

Ever wonder what do goldfish eat? Feeding your pet fish can be a daunting task. Whether you have a aquarium or a pond, this post will help you figure out how to feed your little guys! This blog post is for all the goldfish owners in the world who want to know more about feeding their pets and make sure they’re getting everything they need.

You’ll learn: What type of food do goldfish eat? How often should I feed my fish? What are some common mistakes people make when feeding their pet fish? And much more! So grab a snack (or two) because this long article is full of great information that will answer any questions you may have about feeding your beloved pet friends

What Do Goldfish Eat in the Wild?

Understanding the diet of goldfish means studying what they eat in the wild. Doing so will allow you to understand what kind of diet you need to replicate for them.

As you may already know, goldfish belong to the Cyprinidae family, which means they share ancestry with the carps.

Carps live in slow-moving waters that are rife with plants and vegetation, floating on the surface or thriving underwater. They also eat any animal matter they can find.

So, it makes sense why wild goldfish are natural omnivores. It means that in the wild, they eat plant matter as well as animal matter.

In the wild, plant matter usually means live plants and algae, while animal matter includes insects, insect larvae, zooplankton, tadpoles, and small crustaceans who make up protein sources. Some goldfish might even eat smaller fish.

The main takeaway is this: goldfish will eat almost anything, as long as it fits in their mouth! So, you have to be careful with goldfish food because goldfish truly don’t know when to stop eating.

What to Feed Goldfish

Let’s break this down to a list than I’ll explain in detail. There are four general categories of food types for goldfish:

• Manufactured Foods
• Meat
• Vegetables
• Fruit

Manufactured Foods

This is the goldfish food we are most familiar with when we go into a pet store. These would be:

• Dried pellets
• Dried flakes
• Fish Algae wafers

Lower quality manufactured foods often will have fillers and are not ideal as the primary source of a goldfish’s diet. There are other prepared foods that manufacturers make that fall into our next category.

Meat (Inverts and Insects)

Goldfish love insects and shrimp. These types of food are rich in protein and can be given live, frozen, or freeze dried. The best prepared goldfish foods will often contain these:

• Bloodworms
• Blackworms
• Ghost shrimp
• Brine shrimp
• Squid
• Tubifex Worm
• Daphnia
• Crickets
• Mealworms

Vegetables

Vegetables are a crucial part of goldfish food. The following are vegetables you can feed your goldfish. It’s always best to steam vegetables to sterilize them prior to putting in your fish tank.

• Shelled peas
• Leafy greens such as spinach, lettuce, chard, kale
• Diced broccoli (microwaved or boiled)
• Diced corn (microwaved or boiled)
• Diced carrots (microwaved or boiled)
• Diced zucchini (microwaved or boiled)
• Cooked rice

Don’t believe me? See these Goldfish in action feeding on spinach in Big Fish Little Fish Aquatics video below:

Aquatic plants are also included in this list. Goldfish eat aquatic plants. The cheapest ones to try are Anacharis and duckweed.

Fruits

Yes, goldfish love fruits too! Here are their favorites:

• Grapes (skinned and chopped)
• Cucumber slices (boiled or microwaved)
• Watermelon (sliced)
• Orange (sliced)
• Apple
• Banana
• Stawberries
• Raspberries
• Mangos
• Pears

Pros and Cons of Different Food Types

The diet you can provide adult goldfish pets can be divided into four main categories

• Flake food
• Pellet Food
• Frozen Food
• Live Food

The last two categories are where vegetables and insects tend to be included. Let us have a look at the benefits and drawbacks of each goldfish food class.

Flake Food

Flake goldfish food is the most commonly sought fish food as it is convenient. It is usually a mixture of many ingredients.

It floats in your goldfish tank and gradually falls to the bottom. Dry flake food tends to be very high in protein, which all fish need. However, they should not be the only food you give to your goldfish. Poor quality flake food can contain lots of fillers, which can cause serious health issues for your goldfish such as bloat.

Pros

• Affordable and easy to find in any pet store or aquarium supply store
• It can be dispensed through an auto feeder
• High quality fish flakes can be found with a large roster of nutrients
• Perfect for feeding a large number of fish simultaneously
• Small size is easy for your goldfish to nibble on

Cons

• Does not provide adequate nutrition in most cases
• Cannot be dosed with vitamins
• Uneaten food will dissolve quickly and pollute the goldfish’s tank water
• Some fish accidentally gulp large quantities of air along with the food

Pellet Food

Like fish flakes, pellet food is available in a large variety and can be fed to many different fishes.

And the more you’re willing to spend; the more nutritious your goldfish’s pellets will be. However, unlike flakes, pellets are heavier and tend to sink instead of float, although you can find floating varieties.

Pros

• Their size makes it easier for goldfish to swallow without also ingesting large amounts of air
• Since fish food pellets tend to sink, they can be fed easily to bottom feeders
• High end food pellets tend to be packed with more nutrition than high end flakes
• Easier to measure the amount of fish pellets
• Pellets have a longer shelf life than flakes
• It can easily be used with good automatic feeders

Cons

• Like flakes, pellets can dissolve quickly and pollute the tank water
• Your fish might accidentally eat substrate when foraging for pellets in it

There are many solid brands for goldfish pellets like Saki-Hikari, Blue Ridge (for pond goldfish), and Hikari. NorthFin is a great brand to start with as it’s affordable and high quality.

My Pick

Northfin Goldfish Formula

The Best Goldfish Pellet

Specially designed for goldfish and free from fillers

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Frozen / Freeze Dried Food

Frozen and freeze dried foods offer some of the best healthy offerings for your fish.Frozen foods are generally only available at local fish stores. Look for well known brands like Hikari or San Francisco Bay Brand. For freeze dried, I’m a fan of California black worms with vita-chem.

Pros

• Frozen and freeze dried food contains a large amount of protein, which your fish needs
• Usually not mixed with other chemicals/vitamins except phosphorus
• Strengthens your fish’s immune system
• It helps to promote a healthy and vivid coloration for your fish

Cons

• Prone to dissolving and affecting tank water
• Frozen food must be stored in a freezer

Live Food

Any live food you give your goldfish will probably be their favorite ingredient in their diet. However, it’s important to remember that live food should make up only one part of your fish’s diet and not be the whole of it. Home cultivation of live foods is the safest way to obtain it, but it’s not for everyone.

Pros

• Live food is rich in nutritets and promotes healthy gut bacteria.
• It closely mimic what fish eat in the wild
• They are natural, not processed
• It can help you with setting up breeding conditions
• You can grow and cultivate live food by yourself
• Great for working with finicky eaters
• It tastes much better to goldfish compared to processed flakes/pellets

Cons

• Live foods are much more expensive than store bought foods (unless you raise your own)
• It has a short shelf life
• Messy to cultivate (and likely considered gross by your significant other or roommates 😅!)
• Some live foods can carry and pass on diseases to your fish

Gel Foods

A type of fish food recently growing in popularity are gel foods. These fish foods are available in powder form and must be mixed with water to produce a gel like consistency.

Pros

• Gel fish foods automatically sink to the bottom of the tank, so your fish are less likely to swallow air when ingesting the food
• Their moist texture makes gel foods easier for fish to digest
• They have a high vegetable and protein content
• Pollutes tank water noticeably less than do other food types
• It can be stored in a fridge for up to 2 weeks

Cons

• Gel foods smell bad when boiled
• Has to be prepared in batches
• Expensive

My Pick

Repashy Goldfish Gel Food

Gel foods are a new development in the fish food industry. This food by Repashy includes a mix of inverts like krill and plant matter like Spirulina. Give it a try!

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What Do They Eat Besides Fish Food?

In terms of “human food,” you can feed your goldfish any of the fruits, vegetables, or live food that we have discussed above.

Remember that these foods should be offered to your goldfish at least once a week. You can also create your own recipes for your goldfish. We really like this instructional video by ThinFrog for homemade goldfish food. You can even eat this mix yourself 😊

More importantly, it’s of crucial importance to give them a balanced diet. Read more about that below.

Diet

It’s imperative to give your goldfish a varied diet if you want them to be healthy, live long, retain their coloring, and prevent digestive issues like bloat.

A good staple tank diet can consist of goldfish flakes, pellets, and granules, supplemented with live foods such as brine shrimp, daphnia, and worms (you can find the full list of these foods above).

The inclusion of vegetables is also essential. Shelled peas, duckweed, shredded lettuce, diced carrots—goldfish will eat almost anything (once again, the full list can be found above)!

Meanwhile, the freeze-dried food you give to your goldfish will constitute their carbohydrate needs.

Including floating flakes and sinking pellets in your goldfish diet is a good idea if you have many goldfish in your tank because then all your goldfish can eat equally. Remember, goldfish feed at all aquarium levels.

Nutrition

Here’s a breakdown of the nutritional values you should be aiming to fulfill when you feed goldfish.

Protein

It is the primary nutrient required by goldfish, who need a large amount of protein in their diet.

Protein should make up about 30% to 45% of a goldfish’s diet. Balancing proteins with roughage is essential. This can either be achieved with insect and invert chitin or from fruits and vegetables. I covered chitin and roughage in my Malawi Bloat article. The same principles exist with goldfish and matter more due to their genetic modifications.

Plant protein is easier for your goldfish to digest than animal protein (e.g., brine shrimp), but they do take well to live foods.

Fat

A goldfish needs about 5-10% of fat in its diet.

Vitamins

Goldfish require the A, D, and K vitamins to grow, as well as folic acid. Thankfully, most goldfish can produce their own required vitamins, but you might have to provide supplements now and then.

Minerals

Goldfish need minerals in small quantities. They get it directly from the water, so you don’t have to provide it.

Carbohydrate and Fiber

Goldfish require low amounts of fiber and carbohydrates. Carbs will usually be supplied by the flakes and pellets you give them, and fibers can be had from live plants.

Checking Fish Food Nutrition Contents

When looking at manufactured foods, it is important to check the nutritional analysis and contents of what you are purchasing. Let’s look at an example from Repashy’s gel formula:

Here we see that the protein and fat mix are in the ranges we want. Next we need to look at the ingredients.

Looking at the ingredients, I see a mix of animal matter (Krill, Squid, Egg, Fly larvae), a mix of veggies (Spirulina, Rice, Kelp), and fruits (Watermelon, Banana). This food is checking off the list of everything we want in a balanced goldfish diet.

How Often to Feed

Goldfish owners should feed their pets twice a day, but always according to a set routine. It is important because it helps your goldfish stick to a routine and regulates their diet accordingly.

When it’s feeding time, it’s also fun to watch the little ones get more active and gather near the usual feeding spot. But don’t get taken in when they do this outside of feeding time, because as we keep saying, one of the big no-nos is overfeeding your goldfish.

The next question is how much to feed your goldfish. You should only give your goldfish as much food as they can finish within 2-3 minutes; any more than that, and you risk overfeeding them and overloading your filtration.

The Don’ts of Feeding

Here are some guidelines on what not to do when feeding your goldfish.

Do Not Overfeed

Even if you think your goldfish can eat more after you’ve fed them, resist the urge to give them more food.

Remember, goldfish are greedy little things, and they don’t know when to stop eating, and they willbloat themselves if you allow it (fish even eat their own fish eggs).

If you notice that your goldfish are looking a little swollen, you can safely assume that they’re probably bloated.

Another way of knowing whether you’ve overfed your fish is to look out for a dirty tank. If the tank gets dirty quickly, your fish are producing too much waste.

Do Not Leave Uneaten Food in the Water

Remember, goldfish should not be given any more food than they can eat in 2 minutes or less.

So, if there’s any uneaten food leftover in the aquarium after those 2 minutes are up, you should remove the food manually.

Otherwise, it will disintegrate and dissolve, affecting water quality and, to an extent, making it uninhabitable. Too much waste in the tank water is one of the leading causes of goldfish death.

Do Not Feed Too Much in Colder Temperatures

If the water temperature falls below 45 degrees Fahrenheit or 8 degrees Celsius, feed your goldfish a smaller amount than you usually would. Goldfish are homoeothermic, meaning they can’t digest food as easily at lower water temperatures. This will typically apply to goldfish in ponds.

Do Not Feed Bread

In film and television, people are often seen feeding goldfish crumbs of bread. Do not do this. Bread swells inside the intestines and causes bloating.

Do Not Feed Fatty Food

Mammalian fats, e.g., fat from meat or beef heart, should not be fed to fish as they cannot digest it properly.

Frequently Asked Questions

Closing Thoughts

What do goldfish eat? As we’ve seen, goldfish foods come in a huge variety. Don’t just stick to processed food; remember to switch it up and give them a varied diet by including fruits and vegetables. That’s how you get some healthy, happy goldfish.

And remember, never overfeed, and never leave uneaten food in the tank. Also, look out for large amounts of waste. Leave us comment below if you’ve had any success incorporating these tips into your own routine so that we can share the good news with other goldfish owners out there.

📘 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.

Malawi bloat is one of the most dreaded conditions in the African cichlid hobby, and I’ve seen it take fish quickly when it’s not caught early. The insidious part is that by the time the swelling is obvious, you’re often already behind. Understanding the dietary triggers — primarily too much protein and not enough plant matter for mbuna — is the key to prevention, and that’s where most keepers go wrong.

Malawi Bloat is a term that strikes fear into the hearts of cichlid keepers all over the world. Yes, this is a serious and often fatal illness but you don’t have to lose hope, if caught early enough, treatment is often possible. In this article, we’ll cover the identification, causes, and treatment of this illness so that you know what to look out for, and what to do if it affects your fish.

Overview of Malawi Bloat

Malawi bloat is a disease of the fish’s digestive system that causes swelling and eventually death after a matter of days if left untreated.

What Does Bloat Look Like?

In its early stages, Malawi bloat causes some behavioral changes like hiding and a lack of appetite in your cichlid. You might also see, long, stringy white feces hanging from your fish.

The physical appearance of Malawi cichlid Bloat in its more advanced stages is a bloated/swollen belly that looks like dropsy. The scales of the fish might also lift up, and there might be red markings around its vent. Here is an example of a fish that is recovering from bloat. This was the best video I could find without scaring folks. It’s from Universal Cichlids’ YouTube channel.

Malawi Bloat isn’t the only cause of a swollen abdomen in cichlids, however, so don’t panic too soon. Often, your fish may simply be overfed or constipated. If a bloated cichlid is still eating, you’re in luck, it is highly unlikely to have Malawi Bloat.

What Causes Bloat?

The general consensus on the medical cause of Malawi Bloat is an increase in numbers of a protozoan parasite in the gut of fish. These protozoan parasites, or flagellates as they are also known, are tiny creatures that live in all fish and don’t usually cause any serious harm. The culprit that is to blame for bloat is called Hexmitia. I’ll leave a scholarly article at the bottom of this post that discusses Hexmitia more in detail.

There is also some reason to believe that Malawi Bloat can progress into a bacterial infection, although this is likely to be a result of the increased parasite load that is already causing illness. Some keepers believe the disease is caused primarily by a bacterial infection like dropsy.

The fact of the matter is that there isn’t (at the time of writing anyway) a universally accepted cause.

You may be wondering why parasites and bacteria that occur naturally in your fish could become such a huge problem all of a sudden, and the simple answer is stress. When your fish is under stress, its immune system becomes compromised and parasites and bacteria that are usually kept in check start to multiply.

There are many possible causes of stress, or stressors, for your fish. Some of the most important stressors are:

Poor Diet

Feeding high protein diets to herbivorous fish is thought to be a possible cause of Malawi Bloat. Whether it can be directly linked to the disease is not known for sure, but a poor diet is definitely a stressor in any fish.

Always research the natural diet of your fish to find out if they are herbivorous, carnivorous, or omnivorous. Remember, if they don’t eat meat in the wild, it shouldn’t be on top of the menu in your tanks. Though this is a highly debated topic regarding protein, the real underlining matter is how much roughage the fish is eating. This can come in the form of protein, such as the chitin from arthropods like brine shrimp and krill.

I know it can be difficult to work with frozen food, so I can point you to a pellet that works. This fish food is crated by Ron Demers, an African Cichlid breeder with over 25 years experience. He developed his food line to have the balance of proteins, veggies, and minerals. He removes all the fillers that you would get from lower quality foods. This is about as good as you can get with pellet food.

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Roughage, like with humans are needed to maintain a healthy digestive system. It would make sense you would want this to for your African cichlids. Manufactured foods like flake food will not contain the essential roughage. You will want to seek out more natural and raw foods.

Poor Water Quality

This is a big one folks, and there are quite a few possible causes of poor water conditions in your aquarium.

Inadequate filtration often causes poor water quality in fish tanks. A good filter in a properly stocked and cycled aquarium should keep your ammonia, nitrite, and nitrate levels in check. A filter that can process 4 to 6 times the volume of your aquarium is generally advised. Cichlids are larger, active, and tough on a bioload. One should be looking at upgrading their filtration with quality biological media and filters with large media capacity like canister filters.

Even with the right filter, you should be careful not to feed too much fish food and clean your tank regularly. Get into the habit of performing routine partial water change to keep your water conditions safe.

Water Parameters

Aquarium water chemistry is very important to keeping healthy, happy cichlids and you should always strive to keep parameters like pH, GH, and KH as close to your fish’s ideal values as possible. Be sure to use a water conditioner when adding new water to your aquarium during a water change and use aquarium salt as little as possible as this is thought to be a possible cause of Malawi Bloat. Keep your nitrates at management levels to also reduce the stress on your fish and monitor with aquarium test kits.

Other parameters like incorrect water temperature, low oxygen levels, too much water flow, and unnatural and irregular lighting can also be very stressful for your aquarium fish.

Stocking

Stocking your tank with incompatible species can be a major source of stress and aggression for your fish. Cichlids tend to be territorial and many species are very aggressive in defending their territories, often injuring or even killing other fish in the tank. This aggression is a major cause of stress.

When stocking your fish tank, make sure that all the fish in the tank are comfortable in the same water parameters and make sure that the species you choose are compatible. With many cichlids, you will need to get the ratio of males and females right to avoid aggression.

Tank Layout

The layout of your tank can also have a pretty big effect on the well-being of your aquarium fish. Species that prefer to live in open water can easily become stressed in a crowded tank for example, or a bare tank without hiding spaces can also cause significant stress to fish that live in very rocky areas with a lot of structure.

Any one of these stressors could result in complications for your fish, and often the problem can be made even worse by a combination of factors. As a rule, always do your best to limit all of the stressors mentioned here. It could go a long way towards preventing most of the problems you might pick up in your tanks.

Identification And Symptoms

In the initial stages of Malawi cichlid Bloat, the signs that you have sick fish are mostly changes in behavior like:

• Lack of appetite
• Spitting out food
• reduced activity
• Increased breathing rate

One of the tell-tale symptoms is the feces of the fish will be clear or white-ish and stringy, remaining attached for long periods of time. Normal feces can also occur in long strands but it will be thicker and darker in color. Fish may also struggle to stay right-side-up and may have problems with buoyancy.

If you notice one or more of these symptoms in your aquarium fish, it’s time to act. By the time the disease becomes physically visible, sadly it’s often too late. When the disease becomes advanced, the gut area will swell up, often massively. This is where the term bloat comes from.

Other common physical signs of Malawi Bloat are:

• Ulcers on the skin
• Red marks around the vent
• Lifted scales

Treatment

If you’ve spotted some of the symptoms of Malawi Bloat in your cichlids, act immediately by moving the infected fish to a hospital tank for treatment. If more than one individual is affected, you may wish to treat the entire tank instead.

Do a water test to check all parameters and look for any sign of other stressors in the aquarium. Try to fix any problems you find and go ahead and perform a large water change of up to 40% or so.

Medication

In the past, aquarists often made use of a product known as Mardel Clout for the treatment of Malawi Bloat. Unfortunately, this product has been discontinued and is no longer available.

Currently, the most popular medicine for the treatment of Malawi cichlid bloat is Metronidazole, commonly known as Metro. This is an antibiotic that works on certain bacterial and parasitic protozoan infections.

This drug is commonly sold as Metroplex, Flagyl, or Octozin. It is also used in the treatment of another common parasite-caused illness of freshwater aquarium fish known as hole in the head, or head and lateral line erosion.

Metronidazole can be administered in two ways, orally, or dosed in the water column. Of course, a sick fish affected by Malawi bloat will not eat and so you’re probably going to need to administer treatment through the water column.

At the same time, it is a good idea to feed your other fish a medicated food to prevent any more cases or treat them before they get serious. Again, Metronidazole-soaked food is the best option, even if the other fishes aren’t showing any symptoms.

A great method for preparing medicated food is to use a product like Seachem Metroplex combined with Seachem Focus, which will bind the metroplex with the food and minimize it leaching out in the water. Another great combo is General Cure and Focus.

Seachem Metronidazole

Seachem Metro is great to use with focus as a medicated food supplement option

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To prepare one tablespoon of medicated fish food, Mix one scoop of Metroplex and one scoop of Focus with a little water. Soak your frozen or pellet fish food in the mixture for at least 15 minutes and store this food in a clean container. This medicated fish food can be kept refrigerated or frozen and it should be fed to your fish until any affected fish have recovered, or for up to 3 weeks. Move your affected fish to a hospital tank to keep the disease from spreading and to keep the fish from getting bullied.

Other Treatments

You can dissolve Epsom salt into your fish tank water to further assist your fish by decreasing bloating in the digestive system. Use about 1 tablespoon of Epsom salts per 5 gallons of water in your tank but add it gradually to prevent shock.

You can also feed your fish peas at this time, which should be boiled lightly and allowed to cool. Peas are known to be a natural laxative for fish. During treatment, keep your lights low because this has a calming effect on your fish.

If you’ve been successful in your treatment, the symptoms like swelling should subside and the scales should flatten out. Once your fishes have regained their normal, healthy appetite and begin to defecate normally again, you know you’re back on track.

Another great medication that used to be available was Mardel’s Clout. Unfortunately, it has been banned due to having cancer causing agents. Hoping there can be a replacement in the market eventually as this medication used to be the go to when it came to fighting this disease.

FAQS

References & Further Reading

When it comes to talking about fish diseases, we should use cited scientific articles when available. Here are several to help educate you on bloat and parasites.

University of Florida – Management of Hexamita in Ornamental Cichlids

Klinger, R. & Francis-Floyd, R. Introduction To Freshwater Fish Parasites. University Of Florida, IFAS Extension

Francis-Floyd, R. Stress-Its Role In Fish Disease. University Of Florida, IFAS Extension

Conclusion

Malawi Bloat is a serious disease that often affects African cichlids and other aquarium fish. It’s important to remember that bloat is very scary and can happen at any time. This article has provided you with a number of tips on how to prevent it as well, but if your fish does get bloated there are some medications that will be effective in treating the disease. We encourage everyone who reads this blog post to leave us their thoughts below about what they think causes malawi bloat or anything else they might want more information on. Happy reading!

📘 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.

Ah, goldfish temperature. This is such a contested topic. An oft-repeated adage about goldfish is that they are cold water fish, and therefore should not be put in warm water. This is somewhat untrue.

You might not know this, but Goldfish can live in water of different temperatures. But what’s the range? What temperature is best for a goldfish? Why does it matter so much? Goldfish are some of the hardiest fish you will find, yes. And because of this, they certainly can survive at colder temperatures, but that’s not always the ideal setting for them to thrive in.

In actuality, putting your goldfish in water of the wrong temperature can have irreversible adverse effects, and might even lead to death. You also have to take other factors into account, such as the species.

In this article, we’re covering everything you need to know about goldfish temperature. Let’s get started!

What’s The Best Goldfish Temperature?

The correct water temperature for a goldfish isn’t so easy to figure out given that they can live in a wide range of temperatures. However, for all intents and purposes I’ll give a quick and general answer:

The ideal water temperature goldfish will thrive in is between 65 and 72 degrees F / 18 to 24 degrees C.

Now, the temperature range mentioned above is a general range for all goldfish. But it’s important to remember that these fish are mainly divided into two main categories: fancy and slim-bodied. And knowing about fish types will help you to determine the right water temperature range more easily.

Let’s have a look at the differences between the two types, and the associated temperature conditions.

What is a Fancy Breed?

Also called egg-shaped goldfish, fancy goldfish are characterized by their uniquely beautiful, sometimes bizarre, appearance. These double-tailed fish typically have round bodies resembling golf balls.

The main deal with fancy goldfish is that they are more modified—genetically speaking—than slim-bodied goldfish. It’s also important to understand that these fancy fish are much more prone to freshwater fish diseases if their tank environment is incorrect.

As such, these goldfish need more specific temperature and living conditions, and are better suited to tank living than pond living. They can’t survive in a wide range of temperatures, and as such, they should also not be kept in a tank with overly cold water — or water that is too warm.

Here are some of the most commonly kept goldfish of the fancy variety:

• fantail goldfish
• veiltail goldfish
• telescope goldfish
• pearlscale goldfish
• black moor goldfish
• lionhead goldfish
• oranda goldfish
• ranchu goldfish
• bubble eye goldfish
• ryukin goldfish.

What is a Slim-Bodied Breed?

If you know about comets and shubunkins, you already know what slim-bodied goldfish are. They are one of the most popular choices for novice aquarists. They are much more hardy, fast, and athletic than their fancy counterparts. This allows them to do pretty well in varying tank water qualities and cooler tank temperatures. This suitability to various water conditions makes them suitable for living outdoors. In fact, it’s actually recommended to keep certain slim-bodied goldfish in a pond instead of a tank, because they can grow quite large in size.

Many people wrongly think that slim-bodied goldfish aren’t as attractive as the fancy kind, but this is untrue. You will find many common goldfish with unique and appealing physical traits, such as large nostrils, distinctive head growth, funny eyes and flowing fins. They also come in a variety of colors.

Here are the best known fish in this category:

• common goldfish
• comet goldfish
• shubunkin goldfish
• wakin goldfish
• jikin goldfish.

Fancy vs Slim-bodied Temp Requirements

Now that you know more about the differences between fancy and slim-bodied goldfish varieties, you can probably begin to guess that they have differing tank requirements when it comes to water temperature.

Compared to other fish, goldfish of the slim-bodied variety are much better able to withstand fluctuating temperature changes and environments, such conditions would not only stress out a fancy goldfish but even put them at risk of death.

So, it ultimately comes down to this:

Fancy goldfish should be kept at a tank temperature between 65 and 72 degrees Fahrenheit if you want them to have a long and healthy life.

In contrast, slim-bodied goldfish, as we have already established, are much better able to withstand colder water temperatures resembling those of outdoor ponds. They need a tank temperature between 65 and 72 degrees F, but have the ability to survive winters outdoors and can tolerate higher temperatures better.

Indoor vs Pond Temp Differences

Goldfish are exothermic, which means that their surrounding temperature determines their body temperature. They absorb and release energy from and into the water—which means the bodily functions of this fish are entirely dependent upon the water temperature being correct.

Digestion, immune system, respiration—these are all metabolic functions that are directly affected by water temp. The higher the goldfish water temperature in your tank, the faster these processes will be.

So, for goldfish kept in a tank with a temperature of 75 degrees, for example, you’ll have to provide 5-10 times more food than those kept in an outdoor pond where the temperature might be as low as, say, 58 degrees. In fact, they can actually get much colder. In this example video below by David Cook, his pond froze over and water temperature was around 41 degrees F. You can see the fish are exhibiting dormancy and we can see slim-bodied goldfish in the pond.

When it comes to indoor tank temperatures, you also have to take into consideration the toxicity of ammonia concentration. When the water temperature is higher, the likelihood of poisoning from toxicity in the tank is higher. This becomes a bigger issue in aquariums as the overall tank volume is lower.

Household Temperature Requirements

For fish that you’re keeping in home aquariums, it’s important to take into account the temp range of your household. As a rule, aquarium water is at least 2 degrees warmer than room temperature¹, so you need to take steps to cool your aquarium water by other means. This is particularly true if you’re keeping your pet in a warm climate.

First, ensure that your goldfish tank or tanks are not placed near direct sunlight. Next, you have the option of using your existing air conditioner or ceiling fan to cool the water (in the latter case, it’s recommended to remove the goldfish tank lid to allow the water to cool faster).

Alternatively, if you have money to spare, you might want to look into investing in an aquarium fan or a mobile AC for your fish. Some people like to float ice packs in their goldfish tank, but we don’t recommend this as it can change the tank temperature too much too fast—and that can lead to temperature shock for your pet.

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Working through your room temperature is the best way to manage heater. An aquarium chiller is a consideration, but typically very expensive and not as versatile as a mobile AC solution that can function as a backup system in the event your central AC unit goes down.

Temperature Shock and How to Deal With It

Sudden tank temperature fluctuations can lead to your fish experiencing temperature shock. Changes of even 2 degrees can shock your fish. So, when you’re performing water changes, it’s crucial that you ensure the new water is within 2 degrees of the old water. For this, it’s recommended that you use a digital aquarium thermometer to measure the water temperature.

Now, it’s a very important part of goldfish care to know when your fish might be suffering from temperature shock. Here are the most common symptoms, which are similar to those of oxygen deficiency:

• Sitting at the bottom
• Rapid breathing
• Lethargy / aimless floating
• Excess slime production
• Buoyancy problems
• Gulping at the surface (insufficient oxygen).

If you think your fish have been afflicted by temperature shock, don’t do a big water change to set things right. This can be counterproductive and actually over-stress your fish anew. Gradually bring the water temperature up if it has gone down.

In the case of an overheated aquarium, you can follow the steps we outlined in the above section to quickly but manageably bring the temperature back down. This includes using a fan or air conditioner, or floating a frozen pack in the goldfish water. But be careful of not making the situation worse.

If you live in a climate where you continually face problems of too-hot fish tanks, you might want to consider getting an aquarium chiller for your fish, if you can cover the cost.

Start by lowering the temperature gradually to around 54°F or 12°C. Then, to induce breeding, slowly raise the temperature to 68 °F – 74°F (or 20°C – 23°C). This should help you induce breeding behaviors in your goldfish.

Closing Thoughts

The water conditions and temperatures at which you keep your aquatic pets greatly impacts their health and capabilities. If you want a more low-maintenance fish, we would not recommend getting yourself a fancy goldfish since they require stricter temperature conditions. But for slim-bodied fish, you should be prepared to keep them in an outdoor pond.

Also remember that the temperature of the water in your tank should also be suitable for the other fish inhabiting it. So choose your goldfish tank mates wisely.

If you have any questions about caring for goldfish or want more information on them feel free leave us a comment 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.