Hatchetfish: Care, Size, Lifespan, Diet & More

Hatchetfish (Gasteropelecidae) are species of freshwater fish that are native to South America. They are popular as pet fish due to their unique shape and behavior. Hatchetfish have a round body with thin tails, giving them the appearance of a hatchet or ax when viewed from above. 

In the wild, they can be found in slow-moving rivers and streams where they feed on small insects and crustaceans near the surface of the water. As pets, Hatchetfish are peaceful community fish that should be kept in groups of at least six individuals. 

There are also many other key points to keeping these fish happy and healthy. So we made this guide to help you fully understand these fish and the care they need. So continue reading…

Species Profile & Overview

Hatchetfish fish are native to Central America and South America. They are often found in ponds, ditches, marshes, flooded regions, and slow-moving rivers. 

A large number of them can be found in northern parts of South America and in Guianas. But they can be found in all regions around that area. These fish are distantly related to tetras and share some of their behaviors.

The freshwater Hatchetfish family is divided into 3 genera and has a total of 9 species. The 3 main genres are Carnegiella, Gasteropelecus, and Thoracocharax. We will cover all species below under types of hatchetfish.

Of the 9 known species of hatchetfish, only a few of them are commonly seen in pet stores. However, all these 9 species are coming from the same region and live in similar water parameters. They also need similar care requirements which this guide will cover for you.

These fish inhabit slow-moving or still waters with plenty of vegetation. They spend most of their time near the surface of the water where they can find food. They mainly feed on small insects and larvae that are on the surface of the water.

Hatchetfish are very peaceful schooling fish and will not harm other species. Because of this, you should only keep them with other hatchet fish or any peaceful fish that will not try to harm your hatchets.


The Hatchetfish fish are definitely one of the most unique pt fish you can own. These fish might not be the most colorful species, but they are definitely the most eye-catching fish in any tank. 

Their thin but spread body shape and their flat and fanner pectoral fins make the fish look like a “T” looking from the front. But they look the most magnificent when looked at from the side. With their large round belly and thin tail, they look like hatchets!

All 9 types of hatchetfish have the same body shape but some have unique patterns on their body that set them apart from other species. 

The coloration of this species varies from silvery-blue to greenish-yellow with some specimens having black stripes or spots along their sides. The fins are transparent and light can easily pass through them. 

Overall, Hatchetfish fish is one of those rare finds that add beauty and grace to any aquarium. This is due to their stunning peaceful nature and their unique body shape.

Types of Hatchetfish & Their Size

There are 9 types of hatchetfish known for science. But only a few of them are available in pet stores for sale. Generally, the availability is seasonal as these fish are being collected from the wild. 

While all the hatchet fish need similar care and diet, there are a few differences among them. Below we listed the main types of hatchetfish that often become available. We also mentioned their main differences and their unique features. 

The fish below are listed from smallest to largest type of hatchetfish.

1. Pygmy hatchetfish (Carnegiella myersi)

The Pygmy hatchetfish is the smallest hatchet fish in the hobby. They are peaceful fish that make an excellent addition to the freshwater aquarium. Its size ranges between 0.8 – 0.9 inches in length as adults, making them ideal for smaller tanks. 

Despite their small size, these fish are known for their beautiful colors and patterns. Which can range from bright yellow to silver with black stripes down either side. 

Some Pygmy hatchetfish can be transparent and their internal organs are visible which makes them super interesting fish to own. 

This species requires a well-established aquarium with stable water parameters. Because of their smaller size, they are more susceptible to changes in water parameters. 

2. Blackwing hatchetfish (Carnegiella marthae)

Blackwing Hatchetfish (Carnegiella marthae)
Blackwing Hatchetfish (Carnegiella marthae)

The Blackwing Hatchetfish are very popular in the aquarium hobby due to their striking coloration and body shape. The adult size of these fishes reaches 1.1 inches, making them the second smallest hatchet fish in the world. 

Blackwing Hatchetfish have a dark gray or black stripe on the sides and their body color is often pure silver or silver with a brownish tint that glimmers when they move around in the light.  

They also have a black line running across their belly area from the head to the tail. On the body, they can have small dark sprinkles. A combination of these unique features makes this fish look very different from other species of hatchet fish.

3. Marbled hatchetfish (Carnegiella strigata)

The Marbled Hatchetfish is an elegant and beautiful species that adds beauty to any aquarium. These fish can grow to about 1.4 inches in length making them very small fish for smaller tanks. 

This species also features stunning patterns along its flanks which can range from stripes and dots to intricate geometric designs. These patterns are often black which creates a beautiful contrast against their silver body. 

4. Silver hatchetfish (Gasteropelecus levis)

The Silver Hatchetfish, as the name suggests, has a silver body color but it can have a very thin black strip on the sides. Some individuals can have a broken line creating a dot pattern and some might not have any black on their body. 

In terms of size, adult Silver Hatchets grow to be around 2.2 inches in length when fully mature. While they may appear small at first glance, these little beauties can make quite an impact on your aquarium thanks to their stunning colors and patterns! 

5. Common hatchetfish (Gasteropelecus sternicla)

The Common Hatchetfish is the most available fish in the hobby. They are still beautiful and unique freshwater fish. These fish are commonly mistaken for silver hatchetfish as their appearance looks very similar.

But the main difference between these two species is their size. The Common hatchetfish can grow up to 2.5 inches in length. This makes them slightly bigger than a fully-grown hatchet fish.

The coloration of these fish varies from silver or a pearly gray. They often feature black stripes across the sides of their bodies that add more visual appeal to these fish.

6. Spotted hatchetfish (Gasteropelecus maculatus)

The Spotted Hatchetfish is a stunningly beautiful fish that stands out in any aquarium. Its bright silver body, sleek hatchet-shaped profile, and colorful patterns make it an eye-catching addition to any home aquarium.

While they can look very similar to common hatchetfish, these fish are one of the largest species of hatchet fish you can buy. They are known to grow to about 2.5 inches in length making them a very large variant. 

Aside from their size, the main difference between Spotted hatchet fish and other variants is the number of spots they have on their body. The Spotted variants, as the name suggests, have more spots on their body that makes them look very different from other variants. 

Spotted Hatchetfish (Gasteropelecus Maculatus)
Spotted Hatchetfish (Gasteropelecus Maculatus)

7. Platinum or spotfin hatchetfish (Thoracocharax stellatus)

The Platinum Hatchetfish (a.k.a Spotfin Hatchetfish) is a species of freshwater fish that can be found in the Amazon River basin and rivers of Venezuela, Colombia, Ecuador, Brazil, Peru, Bolivia, Paraguay, and Argentina. 

This beautiful fish has an unmistakable silvery-platinum sheen often with no patches or dots on its body. They are rarely available for sale but make great pet fish for most aquariums. 

Adult size for this species is around 2.5 inches but some specimens have been known to grow slightly smaller lengthwise. This makes them one of the largest species of hatchetfish and at the same time, they are one of the most beautiful of all.


Hatchetfish have an average lifespan of 3 – 5 years. But they can live longer if given the proper care and environment.

The main factors that affect the lifespan of Hatchetfish fish include water quality, diet, tank size, and temperature. With a proper diet, clean waters, and no fluctuating parameters you can expect your fish to live its maximum life expectancy. 

Keeping them at temperatures outside of their preferred range (75-80°F) may cause stress on the fish and result in shorter lifespans as well. Warmer waters generally increase their metabolism and therefore they may live a shorter life.

Behavior & Temperament

Hatchetfish are peaceful species that will not bother other tank mates. They are active swimmers and prefer to stay near the top of the water column, often swimming in groups.

These fish are shy and need to have tall plants so they can hide when under stress. Fast-moving and larger fish can also increase their stress levels so it’s important to pick the right tank mates for them. 

All types of hatchetfish are schooling species and need to live in groups. These fish school at the top of the tank creating beautiful patterns. 

Hatchetfish are known to jump out of the water so you will need to make sure you have a lid over your tank. If you don’t have a lid or cover for your tank, you can lower the water levels as a temporary measure until you purchase a lid. 

Hatchetfish Care

Hatchetfish have some specific care requirements that must be met for them to thrive. The most important aspect of their care is the tank, water parameters, and the diet they receive daily. 

In the next few sections, we will cover all the basic needs these fish have and how to provide them with the best possible environment. 

Tank Size

The minimum tank size for a Hatchetfish fish is at least 20 gallons. This should be considered the absolute minimum as these fish need to live in groups of 6 or more. 

A 20 gallon tank will allow them to have enough surface area and water volume to live frugally. But if you really want to see their true schooling behaviors it’s best to get them the biggest tank you can house.

In a large tank, you can keep more hatchet fish and as a result, you can expect to see beautiful schooling behaviors in the upper section of your tank. Paired with some colorful fish in the middle, your tank will look like a block cut from nature. 

What To Put In A Hatchetfish Tank

Decorating a tank for hatchet fish is easy as these fish stay near the surface of the water. But they still need lots of plants to hide when they are under stress. These fish are shy and will easily get spooked so they need to have someplace to hide. 

The best way to decorate an aquarium for Hatchetfish is to create a natural aquascape that mimics their native environment. This can be done by adding driftwood, rocks, and live plants to the tank. 

Because these fish usually have a shade of silver it’s best to have a black background tank to make the fish more visible. A black background tank with lots of green plants will make a beautiful environment for the fish and the human viewers.

Similar to the black background, you can also pick dark or black substrates to draw the attention of the viewer to the fish and plants. It’s best to pick the substrate based on the type of plants you want to have. 

Since live plants are an essential part of any healthy aquarium, we suggest planting your aquarium as much as you can. Live plants provide oxygen, absorb toxins, create hiding places, and act as natural filters.

For Hatchetfish fish, in particular, plants can help to reduce stress levels by providing areas of shade and shelter. This is especially important if you have other fish in the tank or if the aquarium is in a busy area inside the home.

Almost all freshwater plants can be used with hatchet fish but the best ones are the ones that can grow slightly larger. Plants like Amazon Sword, Jungle Val, Anacharis, Hornwort, Moneywort, and Rotala Indica can be great compatible plants with these fish. 

These fish need some open surface area in their tank. So it’s important to regularly prune plants like Jungle Val or surface floating plants that can cover the surface of the water. 

Light Requirements

Hatchetfish are shy species and because they stay near the top of the water column a strong light can hurt them. High lighting conditions can also increase their stress levels if there are not many places for them to hide. 

At the same time, we need to keep plants with these guys. You can pick low-lighting plants for these fish but these types of plants often stay small and will not provide enough hiding areas for the fish. 

So to solve this, it is important to have taller plants with an adequate light source. In such conditions, the plants can grow naturally and the fish can have shade when the lights are on.

Blackwing Hatchetfish (Carnegiella marthae)
Blackwing Hatchetfish (Carnegiella marthae)

Water Conditions & Parameters

Hatchetfish can tolerate a wide range of water parameters. But they do not like quick changes in water. This means as long as there is a slow translation, these fish will survive in most aquarium conditions.

With that being said, it’s always best to make sure the water parameters are as close to their natural habitat as possible. Coming from amazon, they do prefer slightly acidic conditions than most other fish.

Here is the ideal range of parameters for Hatchetfish:

  • Temperature: 72 – 81 Degrees Fahrenheit
  • pH: 6.0 – 6.8
  • TDS: 50 – 140 PPM

These fish also need very slow flow in the tank. Especially the surface should be still without too much agitation (movement). Lots of surface agitation will increase the stress levels of these fish and they might not be able to eat properly.

Water changes help to remove any toxins or debris that can build up over time, as well as replenish essential minerals and nutrients that plants need. Generally, a good rule of thumb is to change out 10 – 25% of the water each week. 

This amount should be enough to maintain a healthy environment without shocking the fish with sudden changes in pH or temperature levels.

Filtration System

These species need well-established aquariums that can handle the bioload efficiently. Hatchetfish need stable and consistent water parameters. This means a good filtration system is necessary for them.

When buying a filter for an aquarium with Hatchetfish, it is important to choose one that will provide adequate mechanical, chemical, and biological filtration. But it should not create too much surface agitation or current in the tank. 

The ideal filter for these fish is any canister filter that is rated for the size of the tank. If the canister filter creates too much flow you can point the return valve towards the side of the aquarium so the water heats the wall first. This will slow the current in the tank without compromising the filtration. 

Common Diseases and Prevention

Unfortunately, hatchetfish are susceptible to the most common aquarium diseases. The most common diseases that these species may be susceptible to include Ich (Ichthyophthirius multifiliis) and Velvet Disease (Oodinium ocellatum). 

They are also susceptible to bacterial infections such as Columnaris or Fin Rot. 

Poor water quality can cause these illnesses in aquariums by letting harmful bacteria, parasites, and other pathogens grow in the tank. Other factors like bad diet and stress levels can also cause diseases in the fish.

To prevent diseases, it is necessary to keep up with regular maintenance and water changes. Regularly clean out any debris or waste from the tank, and never feed too much food.

Make sure that all new fish are quarantined before being added to a tank. Most hatchetfish and other wild-caught fish often have internal parasites that can easily kill captive-bred specimens. By quarantining the new fish you are eliminating the introduction of disease to your aquarium.

Diet and Feeding Requirements

Hatchetfish are primarily carnivores and insectivores; meaning they feed on small insects and zooplanktons. In the wild, Hatchetfish feeds mainly on small insects that float on the surface of the water. 

Feeding them in captivity can be a challenge as they feed off the surface. Preferably, you should feed these fish high-protein foods that stay floating on the surface. But they can also grab food in the water as they fall. 

The best food for these fish includes high-quality flake foods, live or frozen brine shrimp, bloodworms, tubifex worms, daphnia, mosquito larvae, and earthworm flakes. 

Feeding them two to three times per day is ideal. However, they should only be given what they can consume within a minute or two. Overfeeding can lead to water quality issues and health problems for the fish.

Excess food will not only lead to an increase in ammonia levels, but it can also cause poor water quality and an increased risk of disease for your fish. As mentioned earlier, Hatchetfish are very sensitive to water conditions so feeding less means healthier fish.

Breeding Hatchetfish

Breeding Hatchetfish is not an easy task and only expert breeders should attempt to breed them. This is because they need specific water conditions and environmental events to trigger their breeding cycle. 

Because these fish are being collected from the wild, there are not many aquarists attempting to breed these fish. This means very little is known about breeding these fish in captivity. If you still want to try your luck and attempt to breed these guys you can follow these steps. 

The first step is to create the ideal environment for breeding, which includes providing plenty of plants and hiding places such as driftwood or rocks. The water should be soft and slightly acidic (pH 6.0) with a temperature between 72-78 degrees Fahrenheit. 

High-quality insect-based foods and other high-protein foods like brine shrimp and bloodworms will encourage the female to develop her eggs. They will typically lay their eggs on floating plants so some floating plants are necessary. 

This is all we know about breeding these fish. We personally never attempt to breed these guys and we never noticed any breeding behaviors for these fish under our care. If you have a proven method on how to breed these fish we would love to hear it from you and share it with our readers. You can contact us via the Contact Us page on this website. 

Tank Mates

Hatchetfish are very peaceful fish that can be kept with other peaceful tank mates. They generally do not bother their tankmates, but other fish might try to bully them. This is why it’s important to keep hatchet fish in larger groups as they find safety in numbers. 

Larger tanks will also help your fish to leave in harmony. Larger tanks provide more space for Hatchetfish to swim and explore, reducing the chances of aggression between them and other tankmates. 

At the same time, you will need to house your Hatchetfish with similar-sized fish. Keeping them in a tank with other small, peaceful fish will help them feel secure and reduce the chances of bullying or aggression.

Because hatchetfish live in the upper column of the tank, it is okay to house bigger, but peaceful, bottom-dwelling fish with them. 

Considering these, here are our top picks of tank mates for Hatchetfish:

  1. Cardinal Tetra
  2. Zebrafish 
  3. Siamese Algae Eater
  4. Ember Tetra
  5. Neon Tetra
  6. Rainbow Shark
  7. Kuhli Loach
  8. Guppy Fish
  9. Plecos
  10. Freshwater Aquarium Snails
  11. Freshwater Shrimps
Spotted Hatchetfish (Gasteropelecus Maculatus)
Spotted Hatchetfish (Gasteropelecus Maculatus)


Keeping Hatchetfish in an aquarium is a great way to add some unique beauty and personality to your tank. These fish are very hardy and easy to care for, and they have interesting behaviors that make them fun to watch. 

They also come in a variety of sizes and patterns, so you can choose the perfect one for your aquarium. Their distinctive shape makes them stand out from other fish, and their ability to jump high out of the water adds another level of excitement. 

With proper care and maintenance, these amazing little fish will bring years of enjoyment into any home aquarium!