If you want to own a harmonious, easy-to-care fish, you should definitely adopt a few Hatchetfish for your tank. This peculiar freshwater ornamental fish has been a favorite for many because of their quirky shape. Their affordable price is an added bonus.

These fish come in beautiful, eye-catching colors and patterns, most notably the Marbled and Black-finned Hatchetfish.

Although these small fish are predacious, their passive nature makes them a perfect fit for a communal environment, even in big tanks. But avoid putting carnivorous fish larger than them.

Detailed explanations about their behavior, feeding habits, and the water parameters of the most common Hatchetfish species in the market are provided below. Do check it out for complete info.

Generic Facts about Freshwater Hatchetfish

Quick Species Facts
Scientific name Carnegiella/Gasteropelecus
Other popular names River Hatchetfish
Family Gasteropelecidae
Average Lifespan 5 years
Average size 1–2.5 inches (2.5–6 cm)
Diet Carnivorous
Temperament Non-aggressive
Breeding Egg scatterers
Origin South America
Type Freshwater
Generic Facts about Freshwater Hatchetfish

Habitat and Origin

Hatchetfish are found primarily in South America, in various regions depending upon the type.

Approximately nine to ten different species are found all over Central and Southern freshwater of South America. Their habitat mainly consists of swamps, flooded marshes, shallow lakes, slow-moving rivers, small ponds, and pools of water.

Physical Attributes and Size

Hatchetfish are comparable to the size of smaller Tetras species, approximately 3 inches. It has a weirdly curved lower body that looks like an axe. This makes them stand out among other fishes.

It is flat and wide, just like a piranha, but the lower body is large and curved like a semicircle. The upper body is uniform, with a tiny dorsal fir near its tail.

These fish have unusually long pectoral fins that look like the wings of an Albatross. These specialized fins provide thrust for jumping out of the water.

Almost all their fins are transparent or semi-transparent, depending upon the fish. It has big round eyes, and the mouth is faced toward the top with the lower lips strongly curved upwards.

Popular Varieties

There are many types of Hatchetfish, but some are more desirable than others in the fish market.

The Silver Hatchetfish has a very shimmering silvery appearance, which makes it preferable over the Common Hatchetfish.

Popular Varieties - Silver Hatchetfish
Silver Hatchetfish

But the Marbled Hatchetfish is the most popular among aquarists because of the swirling, veined-like patterns of brownish-black and white all over the body.

Types of Hatchetfish - Marbled Hatchetfish
Marbled Hatchetfish

The Pygmy Hatchetfish is the smallest, with a maximum size of 2 inches, both in the wild and captivity. It is attractive and highly sought after because of its semi-transparent body. You will be able to see its organs right through them. Not only that, but their lower body is slightly less curved than the usual Hatchetfish shape, which makes them more unique than others.

Pygmy Hatchetfish
Pygmy Hatchetfish

Another variety known as the Black-Winged Hatchetfish is also quite quirky looking. It also has a silvery appearance with a prominent black line present around the body. There are also tiny black striations and patches exclusively at the belly section.

Recently, a rare Hatchetfish species known as the Spotted Silver Hatchetfish was spotted by a local fish enthusiast in Columbia. It has a similar shiny appearance to the Silver Hatchetfishbut has a black lateral line along with numerous tiny black dots around it and can reach almost 3.5 inches in length. However, one peculiar behavior was observed among them during captivity. Generally, Hatchetfish tend to stay near the surface of a water body, but this variety likes to dwell near the middle section of the tank.

Spotted Silver Hatchetfish
Spotted Silver Hatchetfish

Life Expectancy

These fish live for a maximum of four to five years. And according to numerous owners, they live longer and more content if kept in a school.

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It does not matter if it is the same variety because Hatchetfish is naturally non-aggressive. Additionally, having an equal number of male and female fish will ensure less competition and keep them happy.

And as usual, maintaining proper water temperature, a rich diet, and removal of ammonia in time will guarantee a long life expectancy.

Quick Tip – Some owners like to use water conditioners, which help keep the chemical imbalances under control. But this should be followed by timely water changes. This helps improve the average lifespan of your Hatchetfish.

Male vs. Female

It is hard to classify the sex of small fish species like Hatchetfish just by observation unless you rear them for a long time.

Both genders have an equal number of fins. Both their appendages are of equal length, and there are no color differences.

The female is slightly sizeable, and the lower body is more curved than the counterpart. But the size difference between both genders is marginal, so it is hard to anticipate just by looking at them. Measure them using a precise scale to check the length. This, along with the degree of curviness of the body, will help you identify the gender more accurately.

The female’s lower body becomes more rounded than usual when carrying eggs. So determining the sex of the fish becomes easier during mating season.

Other than that, there are no physical differences in Hatchetfish, which makes each gender unique.

Price and availability

Hatchetfish are cheap and a common sight in any local fish store. They can also be bought online within a price range of $4.00 to $8.00.

Some can be over $15, like the Albino Silver Hatchetfish, a rare genetic mutation that gives the fish a pinkish transparent white color and red eyes.

Care Guide

What to feed your Hatchetfish?

Hatchetfish mostly eat nymphs and little aquatic bugs in their natural habitat. They actively hunt for insects that fall on top of the water bodies.

So, a generic diet of worms (grindal worms, bloodworms, earthworms, and blackworms), gut-loaded brine shrimps (live or frozen), krills, and even mosquito larvae are followed. Hatchetfish also like wingless fruit flies, which are considered delicacies.

All these are inexpensive and can easily be obtained from a local pet store. Both live and frozen will do.

They can be skeptical of commercial fish food, such as flakes or pellets, if they have not eaten them before.

So, you can include a few pellets every time you give them worms, slowly developing their habit of recognizing them as food.

It is much easier to develop this behavior if you raise them from a baby. Otherwise, it will take a substantial amount of time to adapt to this.

Pro Tip – Make sure to give food that does not sink too fast, like pellets or flakes. Hatchetfish do not generally go down to eat them. A feeding apparatus is also a good option. This can be opened during feeding time and closed when desired. Although, this is best suited for live fish food.

Behavior and temperament

Even though Hatchetfish are strictly carnivorous, they are not aggressive at all. In fact, they are shoaling fish and will stay happier in a group than alone.

A group of Hatchetfish will always be seen together, even moving in packs. They swim near the top portion of the tank and rarely go down.

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Another fascinating fact about these fish is they can jump out of the water. Their big pectoral fins, mentioned in the section above, and strong muscles are specially used for this. In nature, jumping out is used as a hunting tactic or to escape predators.

This is sometimes seen in captivity, and the fish might end up on the floor. You should be extra cautious when keeping Hatchetfish.

Pro tip- If possible, avoid filling the tank up to the brim. Maintain the height of the water lower than usual, and install a secure lid to prevent the fish from jumping outside.


According to many Hatchetfish owners, it requires a lot of expertise and understanding of the perfect conditions where most activity is seen.

These fish are egg scatterers and are reported to mate during the early monsoon. They spawn eggs during daylight or twilight.

We will cover the basics of their mating habits and what is expected after successful breeding.

However, if you wish to commit yourself to this, understand your fish first and do thorough background research on the type of Hatchetfish you own.

  • The best water temperature should be around 84 to 86 degrees Fahrenheit, with a proper day/night cycle lighting system. The diurnal cycle is vital as spawning happens during daylight, or near dusk.
  • The male will swim around with the female to stimulate her to release the eggs. The eggs will be deposited on the plant surfaces, floating near the top. So, it is crucial to have a few floating vegetation around.
  • After a successful spawn, the male will externally fertilize the eggs and leave them for incubation.
  • It takes about a day or two for the eggs to hatch. Hatchetfish parents will not eat their own eggs, but they do eat their own fry, mistaking them for tiny insect larvae.
  • Rearing babies is not very difficult as compared to breeding adults. You can feed the babies infusoria (tiny freshwater organisms), Nauplii (larvae) of brine shrimps such as Artemia, and Nauplius of water fleas like Daphnia.

Once they grow to double their original size, they can be fed ground-up flakes or pellets. Keep the diet variety as much as possible to provide complete nutrition to the juveniles.


The most noticeable illnesses that affect them are:

  • White spots or Ich.
  • Skin lesions.
  • Bacterial or fungal infections which can also lead to fin rotting.

Tapeworms or parasitic protozoan can also invade their intestines. This can come from untreated fish newly bought from a store.

If you do not put the new fish in a quarantine bath, they can spread illness to your existing fish, which can be devastating. This can be prevented using various methods.

Tank Recommendations

Different species of Hatchetfish have different requirements. We have mentioned the most common ones in the following-

Type of Hatchetfish Marbled Silver Pygmy Black-finned
Minimum Tank Size 20-gallon 20-gallon 10-gallon 15-gallon
Temperature 75°F to 81°F 74°F to 83°F 73°F to 79°F 74°F to 83°F
pH Level 5.5 to 7.5 5.8 to 7.1 5.5 to 6.5 5.8 to 6.9
Hardness 2 to 14 dKH 2 to 14 dKH 2 to 10 dKH 2 to 12 dKH

Tank Setup


The best substrate would preferably be sand or big pebbles. Sand is recommended more because it is easier to clean than pebbles.

Food that sinks to the bottom is not eaten by the Hatchetfish. This can decompose over time, increasing the ammonia levels if not cleaned up.

White or normal brown river sand is the usual choice. This also helps mimic their lake or river, the natural habitat.


The best kind of plants for Hatchetfish are floating ones. These provide a safe place to hide or rest if they feel uncomfortable.

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Hatchetfish will mostly dwell around the roots of these plants and even lay eggs there. So, those are better than substrate-based plants. A few common examples are-

  • Red Root Floaters
  • Water Spangles
  • Dwarf Water Lettuce
  • Live Duckweed Plants
  • Hornwort Bunch Plants
  • Amazon Frogbit 

However, having a few high oxygen-producing rooted plants, such as Green Cabomba, Anacharis, Eelgrass, etc., is also recommended.

Another thing to consider is the Marbled Hatchetfish is a lot more active than its cousins and requires a lot of free space to move around. Therefore, it is advised to house them in a bigger tank with fewer plants.


You can get crafty with your decorations because they spend most of their time in the upper section of the tank. So you can put whatever you like.

Plastic-based decorations can also be used but choose them cautiously. Avoid items that have sharp edges, as they can harm these delicate Hatchetfish.

Lighting Requirements

Moderate lighting is good enough. However, the Black-finned Hatchetfish prefers a more subdued environment because of their natural habitat.

So, a few fluorescent bulbs will compensate. But more importantly, maintain a day/night cycle manually or automatically.

This is important for the well-being of the fish, as it helps them maintain a proper biological clock. Also, these fish are not nocturnal, so they require adequate daylight.

Filtration & Apparatus

Hatchetfish are not very hardy. They are super sensitive to elevated nitrogen levels of ammonia. Thus, an efficient filter is a necessity for the tank.

Alongside it, an air pump is also preferred to maintain oxygen levels. And this also creates turbulence in the water, mimicking their natural habitat.

Suitable Companions

Freshwater Hatchetfish are peaceful creatures and do well in a community tank with other fish. Having said that, Hatchetfish are shy and stay hidden if there are sizeable fish around.

It is not advisable to put predators such as Cichlids or Oscars, as they will instantly eat these little Hatchetfish the moment they see them.

The best companions for them are-


Is Marine Hatchetfish the same as Freshwater Hatchetfish?

No, they are not. Marine Hatchetfish are very distinct from the freshwater ones that live deep in the ocean, around 700 to 3000 feet under. Coincidentally, they look similar but are genetically different.

They are small but cannot be kept in a home aquarium because it is impossible to simulate the high pressure their body requires to sustain.

These Marine Hatchetfish look terrifying when compared to freshwater Hatchetfish. Although they mostly eat zooplankton and other tiny sea creatures.

What kind of fish is a Hatchetfish?

Hatchetfish are purely freshwater or marine. The freshwater varieties are closely related to Tetras, but the marine Hatchetfish are not. This genus diverged from the phylogenetic tree of tetras and evolved into its own variant.

The marine Hatchetfish is from a different family from the freshwater variety and has adapted itself to live in deep sea waters.

How many Hatchetfish should be kept together?

They are schooling fish, so you should keep at least six of them together. It would be even better to keep an even number of males and females.

Keeping them in a smaller group makes them less active, and some have been seen living a shorter life than usual when kept in smaller groups.

Can Hatchetfish live with Guppies?

Yes, they can live with guppies. Although their water parameters are a bit different, with monitoring and adjustments, they can be kept together in a tank.


Hatchetfish are unique in their appearance and will definitely make your tank look special. They are small and active, which makes them the perfect pet to look at after a stressful day.

Hatchetfish are a bit more sensitive than most freshwater fish. So, it can put them at risk of getting sick if not cared for properly. But with a basic understanding of their needs, it is not that difficult to rear them.

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About the Author

Shelby Crosby

Shelby is a passionate fishkeeper who has been writing about fish for over 5 years. She is a pro aquarist and holds a BSc Honors Degree in Wildlife and Fisheries. She creates her own beautiful aquarium layouts and loves to share her knowledge of tropical fish with other hobbyists. Career Highlights: Has worked with several…

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