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Forget about interesting-looking freshwater fish, let’s about tropical fish that fly!
Hatchetfish, also known as common hatchetfish, or river hatchetfish is the most bizarre-looking fish you’ll ever find. Not because of their unusual colors or erratic nature. But because of the shape of their body that resembles a hatchet. Hence, the name.
In this article, we will discuss everything about the hatchetfish species. From their unique body shape to their feedings and breeding, there’s much more to cover.
Let’s jump in further.
- Hatchetfish get their name from their unique ‘Hatchet-like’ body shape.
- It is a peaceful community fish that enjoys the company of at least 6 to 12 fish.
- They are the only true flying fish with large pectoral muscles that work like wings.
- Many species of hatchetfish have bioluminescence with their own pattern of lights in order to communicate, attract prey, and camouflage.
An Overview Of The Fish Species
|Scientific Name||Gasteropelecus sternicla|
|Common Names||River hatchetfish, common hatchetfish, silver hatchetfish|
|Origin||South America in Brazil and in the southern tributaries of the Amazon river basin|
|Tank Level||Surface dwellers|
|Minimum Tank Size||20 gallons|
|Temperature Range||72 – 81° F|
|Water Hardness||2 – 15 dGH|
|pH Range||6.0 – 7.5|
|Difficulty to Breed||Difficult|
|OK, for Planted Tanks?||Yes|
Origin And Habitat
Linnaeus in 1758 discovered the common hatchetfish; Gasteropelecus sternicla species. They originate in South America in Brazil and mainly in south and central America (Southern tributaries of the Amazon river basin). Common hatchetfish are also found in the small streams of Guyana and Surinam with dense vegetation (floating aquatic plants).
In their natural habitat, they are found in regions that are densely populated with aquatic plants. In the wild, the common hatchetfish are mostly found at the water surface and retreat occasionally when threatened or in danger. Mostly, you will find these fish species flying from the surface of the water, trying to catch flying insects.
Fun Fact: Certain hatchetfish species participate in the largest migration in the world, migrating from 1,500 meters (about 5,000 feet) of depth to shallower seas. They gather with their twilight zone neighbors in the shadows to eat at the zooplankton feast, where they consume crustaceans, copepods, floating fish larvae, mosquito larvae, and ostracods. But as soon as the sun comes up, it's time to head back to the twilight zone. The hatchetfish has no control over when the axe will fall.
The Definition Of Hatchetfish
The common hatchetfish species go by their scientific name, Gasteropelecus sternicla. They are known for their unique but strange-looking body that looks like the head of the hatchet. Hence, the term Gasteropelecus in their scientific name also refers to a hatched-shaped belly.
One of the leading reasons for their popularity is not their particular body shape, but their ability to leap from the water’s surface and fly through the air. River hatchetfish or common hatchetfish can also flap their large pectoral fins and catch flying insects. Thus, in the fish-keeping world, the hatchetfish bag the title of the only true flying fish.
Species of hatchetfish are able to fly more than 4 feet and move their pectoral fins like a bird’s wings in the air. As astounding as it sounds, the flying power of hatchetfish is a problem in hatchetfish aquariums as this ability also develops the need for a tight-fitting lid.
The common hatchetfish are small, shiny silverfish with a hatchet-shaped bodies. They are tropical fish found in mostly warm temperature regions at a depth of around 200 to 1000 meters.
Hatchetfish have deep bodies that are flattened from side to side. The tails are slender with big eyes. The common hatchetfish are often mistaken as their cousin relative, the silver hatchetfish. However, the common hatchetfish species are slightly larger than the Silver hatchetfish.
What Is The Average Size Of These Tropical Fish Species?
The average size of Hatchetfish is around 2.6 inches in captivity. However, the wild-caught fish is a bit smaller in size, around 1 1/2 inches.
How Long Do They Live?
On average, hatchetfish lives for about 3 to 5 years in captivity. Since they are social and peaceful fish, it is recommended to keep a group of 8 or more fish to improve their life quality.
What Are The Different Types?
There are five different species of hatchetfish found in the aquarium hobby.
The most common type of Hatchetfish is the silver hatchetfish. They have silver bodies that seem almost transparent and a unique ‘hatchet-like’ body shape. The silver hatchetfish are great swimmers and are known for their ability to jump out of the aquarium. Therefore, always choose a tight-fitting lid for your aquarium.
The Blackwing hatchetfish are larger than the other species of hatchetfish. They grow around 3 inches in length with darker bodies adorned with metallic green or blue hues on the fins. Temperament-wise, they are semi-aggressive fish but generally peaceful fish, ideal for a community tank.
The marbled hatchetfish are somewhat similar in appearance to the popular silver hatchetfish. However, they have smaller bodies and marble-like mottled coloration on their bodies. Marbled hatchetfish are schooling fish that enjoys the company of other species of hatchetfish. Thus, I advise keeping a group of 8 or more to keep your fish healthy and thriving.
Carnation hatchetfish are the species that experienced fishkeepers would enjoy. That’s because they are sensitive to water quality and conditions, so little attention is required. Size-wise, they are a smaller species with a pink or peach-colored body.
The smallest species of hatchetfish are the pygmy hatchetfish (video source). They grow only up to 1 inch in length. Also, they have silver bodies with a black stripe along their dorsal fin.
Common Hatchetfish Care
The freshwater Hatchetfish is a particularly hardy fish. However, it is still recommended for aquarists with some previous fish-keeping experience. That’s because they are active fish and need lots of free swimming space. Also, they are highly prone to fish diseases such as Ich, especially when introduced to a new tank.
Therefore, it is recommended to quarantine the new fish before introducing them into the community tank.
Are they hard to care for?
No, they are not difficult to keep and care for. However, you need a certain level of expertise in keeping their water conditions optimal. Species of hatchetfish are sensitive to water conditions. Therefore, a little maintenance goes a long way. It’s crucial to maintain your tank and clean all the decomposing organic matter, check water quality regularly, and clean fish waste.
These toxins pollute the fish tank and affect the wellness of your fish. Therefore, to cater to these water conditions, I recommend replacing the water on a daily basis. If your tank is densely populated with a group of fish, at least 50% of the water should be replaced every week.
The natural habitat of hatchetfish undergoes rainy season and floods. So, thankfully, they can survive in a wide range of pH, GH, and other water parameters. Hatchetfish are tropical freshwater fish that appreciates water temperature between 75–80°F.
Since they are schooling fish, they thrive in a group of 6 to 12 or more. I recommend keeping at least 12 fish in the community tank because they feel safer and more comfortable. Though hatchetfish are active fish, but not exceptional.
Therefore, the minimum tank size should be 20 gallons or larger. Regardless of the tank size, install a tight-fitting lid or hood because you will find them jumping out of the aquarium often. Besides, if you have installed a filter, heater, or pumps, you are sure to cover any openings with aquarium-safe materials such as craft mesh, etc.
Hatchetfish are not super active fish but they do require free swimming space, considering the fact that they thrive in a community of at least six fish.
The minimum tank size should be 20 gallons. I recommend a long tank with sufficient surface space as they tend to jump out of the water.
A classic 20 gallon aquarium in its 30 inch long variant. A very popular aquarium.
Even though hatchetfish are moderately hardy aquarium fish. There are specific water parameters to maintain for them to thrive in your aquarium.
- The ideal water temperature should be between 75–80°F.
- Hatchetfish prefers slightly acidic water with a pH between 6.0 to 7.5 and it’s crucial to maintain the ideal pH range because changes in pH lead to stressful behavior in the fish.
- They thrive in slightly hard water so the water hardness should be between 2 – 15 dGH.
- Ammonia and nitrites are toxic for hatchetfish and harmful to their overall health. Therefore, install filters to avoid ammonia and nitrite buildup and test your water daily.
- Nitrates: Hatchetfish can survive low levels of nitrates, but high levels can be detrimental to their health. Therefore, consider keeping nitrate levels as low as possible. The ideal range is less than 20 ppm.
- Water movement: Hatchetfish are slow-moving fish that mostly swims at the top of the aquarium. They prefer slow-moving water and gentle current. The use of a filter is recommended, and aeration should be minimized to keep them healthy.
Filtration And Aeration
Hatchetfish are highly sensitive to ammonia and nitrites. Therefore, installing a quality filter is important.
If you have a small tank of around 15 gallons, Hang-on-back filters are easy to install and maintain, and they provide excellent filtration. However, if you have a larger aquarium of around 20 gallons or more, I recommend installing canister filters as they are more powerful than HOB and ideal for larger aquariums.
For hatchetfish tanks, I advise installing sponge filters as they don’t produce strong currents and are gentle.
No matter what type of filter you use, it’s crucial to clean and maintain them daily for efficient results.
For aeration, it’s important to avoid strong currents in the tank as they can lead to stressful behavior. The use of air stones and air pumps is recommended for tank aeration.
Hatchetfish occupies the surface of the water tank and does best in tanks with moderate to low lighting. Therefore, the ideal lighting for hatchetfish is moderate to low, depending on various factors, including plants, and species of hatchetfish. Low light aquarium plants are most ideal for them.
Aquatic Plants and Decorations
Aquatic plants and decorations are important for a hatchetfish tank because it provides hiding places and a fun natural environment for your fish. That’s because their natural habitat is laden with hiding places and vegetation. Also, plants improve the quality of water by absorbing excess nutrients and promoting a healthy balance of microorganisms in the water.
Some of the best aquatic plants for your hatchetfish are:
- Floating plants: Amazon Frogbit, water lettuce, Salvinia, etc.
- Mosses: Java Moss, Christmas Moss, etc
- Other plants: Java Fern, Anubias, Cryptocoryne, etc.
For decorations, it is recommended to add driftwood, rocks, and stones to create a natural environment for your fish.
Manzanita offers it all. Great shape, low tannins, quick to water log and reasonably priced. It's the ultimate driftwood!
Freshwater hatchetfish are simple to keep and take care of. To maintain their water in the best possible condition, you need to have a particular level of competence. Because hatchetfish species are sensitive to water quality, a little upkeep may go a long way. Maintaining your tank is essential, as is cleaning out all of the fish waste, nitrate, nitrite, and phosphate buildup.
These chemicals contaminate the fish tank and harm your fish’s health. I advise refilling the water every day in order to address these water conditions. If you have a lot of fish in your tank, you should change the water every week by at least 50%.
Hatchetfish are surface dwellers. Thus, choosing a substrate for their tank is not challenging. However, you need to consider the size of the tank, and the type of plants in your aquarium before choosing the right substrate.
Fortunately, you can keep any substrate you want as long as it suffices your tank’s needs. Fine sand is the most popular option for substrate because it does no harm to your fish’s fins. Gravel and Aqua soil are also common substrate options.
Community Tank Mates
Hatchetfish are peaceful fish that are relatively shy. Therefore, they should be kept with compatible fish that is not hostile or aggressive towards them. Since they are schooling fish, always keep them in a group of 6 or more.
The bigger the school, the happier the fish. Some of the suitable tank mates for hatchetfish are:
What Do They Eat?
Hatchetfish are carnivorous fish that mostly feed on crustaceans and insects in their natural habitat. They have their mouths on the top of their bodies so they prefer eating surface foods such as fruit flies, mosquito larvae, and small vinegar flies.
In captivity, they accept live food, fish flakes, flake foods, and frozen foods. Basically, any food that is on the surface of the water. It’s recommended to feed them protein-rich food such as brine shrimp or blood worms, daphnia every day, etc. You can also feed them vegetables occasionally such as blanched spinach, zucchini, and cucumber.
Best Tropical Fish Flake Food
Cobalt offers a premium level flake food with probiotics. A color enhancing formula that works great for all tropical fish
What Is The Feeding Frequency?
You should feed them several feedings a day. Ideally three times a day. However, make sure not to overfeed your hatchetfish otherwise, it will create health issues or water quality problems.
Hatchetfish are egg layers. But in captivity, the common hatchetfish has failed to breed. However, the marbled hatchetfish are hardy and easy to breed as compared to other species.
Overall, the breeding of hatchetfish is challenging, but with the right conditions, it’s certainly possible.
Choose A Breeding Tank
Hatchetfish need a spacious tank with lots of hiding places, floating plants, and other] vegetation. Adjust the lighting to mimic daylight or use some natural sunlight to escalate the process. The breeding tank should have ideal water parameters with a pH range of around 6.0 to 7.5
Feed The Breeding Fish
Feed your breeder fish with high-quality protein-rich food that includes live or frozen foods such as daphnia, mosquito larvae, blood worms, and brine shrimp. This will help in the breeding and spawning process. Once they are well-fed and nourished, introduce the pair into the breeding tank.
The Perfect Timing
Hatchetfish breed in the early morning hours, therefore, mimic the natural environment of fish in the breeding tank. Gradually increase the light intensity and then reduce it in the evening to trigger the breeding behavior.
Keep An Eye On The Floating Plants
You will find the fish eggs mostly on the underside of floating plants or on the tank glass. Remove the adult fish as soon as they lay eggs as the adult fish might end up eating eggs. The fish eggs hatch in around 3 days. The baby fish need to be fed small amounts of brine shrimp with other small live food at least thrice a day.
The hatchetfish are susceptible to Ich. Therefore, it is crucial to quarantine the new fish in a separate tank before introducing it to the community tank. However, if you don’t keep a check on water conditions, there are higher chances of your fish developing diseases.
Like most fish, these freshwater fish are subject to many other fish diseases, such as skin flukes, parasitic infections, and fungal or bacterial infections. Despite being hardy, these fish species still get diseases. Thus, whatever you add to your aquarium—new fish, tank decorations, aquatic plants, substrate, properly clean and quarantine everything before moving to the main tank.
How Many Should I Keep?
Hatchetfish enjoys being in a school of at least 6 to 12 and even more.
What Fish Can Live With Them?
They are peaceful fish that are also shy. Therefore, they should be kept with compatible fish that is not hostile or aggressive towards them. The ideal tank mates for hatchetfish are:
Are They Easy To Keep?
Yes, they are hardy and easy to keep. However, they are not recommended for beginners as they demand particular water conditions and tank maintenance.
What Do They Eat?
They are carnivorous that need a diet rich in protein. Frozen foods, live food, frozen fried foods, meaty foods, brine shrimp, tubifex, fruit flies, and daphnia are excellent sources of nutrition for Hatchetfish.
Are They Aggressive?
No, they are very peaceful and non-territorial. In fact, they are a great choice for a community tank. However, if they are kept in small tanks or containers where they feel threatened, they might become semi-aggressive toward other hatchetfish.
Are They Hardy?
Yes, they are moderately hardy fish recommended for aquarists with some prior experience.
Hatchetfish, like their unique name, are interesting and intriguing fish with unusual bodies, shimmery scales, and peaceful nature. The fish species, despite their many different types, share similar characteristics and behavior. Hence, ideal for community tanks and a treat to watch and care for.
Mark is the founder of Aquarium Store Depot. He started in the aquarium hobby at the age of 11 and along the way worked at local fish stores. He has kept freshwater tanks, ponds, and reef tanks for over 25 years. His site was created to share his knowledge and unique teaching style on a larger scale. He has worked on making aquarium and pond keeping approachable. Mark has been featured in two books about aquarium keeping – both best sellers on Amazon. Each year, he continues to help his readers and clients with knowledge, professional builds, and troubleshooting.