Marble Hatchetfish: Species Overview

Category: Hatchetfish

Common Names: Marble Hatchetfish

Scientific Name: Carnegiella strigata

Family: Gasteropelecidae

Minimum Tank Size: 20 Gallons

Care Level: Moderate

Temperament: Peaceful

Max Size: 2 Inches

Temperature: 75-80 F

pH: 5.5-7.0

Tank Level: Top

Colors: Orange, Red, Tan, Black

Diet: Carnivore

Breeding: Difficult

Dawson [CC-BY-2.5]

Marble Hatchetfish: Species Overview

The marble hatchetfish is a popular choice for tropical aquariums because they add color and life to the top of the tank. In fact, they add so much vibrancy that if you spook them, they’ll jump into the air and try to fly out of the tank.

Since marble hatchetfish are notorious for flying out of their tank, keeping the lid closed and preventing fast motions that can spook them is vital.

Between their jumping behavior and sensitivity to the wrong water parameters, marble hatchetfish are best for intermediate and advanced fish keepers.

Distinguishing Features

If you imagine a hatchet when hearing “marble hatchetfish,” you’re not far off.

When looking at hatchetfish from the top, they have a narrow triangular shape. But when you see them from the side, their most noticeable feature is a massive, flat rounded belly that dips down from the “handle” of the hatchet.

Their belly drops from the back of the lower jaw to close to where their tail begins. At that point, the marble hatchetfish’s body tapers off into a thin, straight shape.

Marble hatchetfish have three distinct fins—two on the top of their body and one on the bottom. They also boast a forked tail with the bottom portion of the fork slightly longer than the top.

The “marble” part of the hatchetfish’s name stems from the fact that these fish have black and silver bellies in beautifully inconsistent marble-like designs.

A marble hatchetfish’s topmost part is brownish-gold, contrasting with its marbled belly. Depending on the lighting, you can often see hints of the following colors on these fish:

  • Silver
  • Pink
  • Brown

These colors give off a sheen that makes marble hatchetfish even more captivating to watch as they dash around the top of your aquarium.

Finally, marble hatchetfish have two dark stripes on either side of their body, with the color intensity varying according to the fish.


Marble hatchets originate in the Amazon of South America, where they thrive in the freshwater of brooks, marshes, flooded areas, and river tributaries.

As a result, they hold up well in cloudy water. But you should never let your tank water get murky, for that’s a sign of toxin build-up.

Marble hatches live at the top of the water, so they pay little attention to the substrate beneath them. Nevertheless, in the wild, they live in areas with sandy and muddy bottoms.

This species commonly encounters floating aquatic vegetation in their natural environment, such as the giant water lily and Amazon frogbit. They also encounter fallen plant debris and sticks from nearby land-based plants.


Marble hatchetfish are a relatively small species, growing up to 1.5 to 2 inches long as adults.

One of the most effective ways to differentiate between male and female marble hatchetfish is that the females are almost always larger.

The females also typically have thicker bodies and rounder bellies, especially when they’re on the verge of spawning.


Marble hatchetfish have a shorter lifespan than many species of tropical fish in captivity, averaging about two years. This relatively brief existence can be partly attributed to the fragility of the species

Nevertheless, your marble hatchetfish could live as long as five years with excellent care and a dose of luck.


Unfortunately, there aren’t many indicators to help fish keepers determine males from females. The most reliable method is comparing the fish’s size.

Female marble hatchetfish typically grow slightly larger than males and have a girthier appearance.

But if you happen to have a school of marble hatchetfish in your tank that are all the same gender, there aren’t any distinctive markings or coloring that could help you determine the sex of your fish.


Marble hatchetfish have an excellent reputation for being peaceful fish. They’re highly social within their species, so you should keep a minimum of six fish in your tank.

They also get along well with other fish of a similar size. But since marble hatchetfish would rather flee than fight, it’s vital to keep aggressive fish species out of their tank.

Both male and female marble hatchetfish have equally peaceful tendencies, except during mating when males will chase females.

Tank Parameters

Marble hatchetfish can be challenging to care for, given that they’ll become ill fast if their tank parameters fall outside their preference. So, follow the guidelines below to ensure you keep your fish in optimal health.

Minimum Tank Size

The minimum tank size you need for six marble hatchetfish is 15 gallons. That requirement comes out to 2.5 gallons per fish.

But the number of gallons isn’t the only important aspect when selecting a tank. Instead, the tank must have lots of open area at the top, as that’s where your marble hatchetfish will prefer to congregate.

Water Parameters

Below are the water parameters you should establish in your tank before adding your marble hatchetfish.


Marble hatchetfish love warm water. You should keep their tank between 75°F – 82°F.

Purchasing an aquarium lamp and checking the temperature every day is vital to keeping your hatchetfish healthy.


Marble hatchetfish enjoy acidic water with a pH between 5.5 and 6.6.

That said, if the temperature approaches neutral (7.0), they can often tolerate it. But, like all of the water parameters that we share, it’s best to aim for the middle of these ranges.

With that approach, you give yourself some wiggle room if you need to increase or decrease any water parameter.


As freshwater fish, the marble hatchetfish doesn’t require salt in its aquarium for survival.

Still, some fish keepers occasionally add small amounts of aquarium-approved salt to boost the marble hatchetfish’s immune system.

As a result of its immune-boosting powers, salt is also useful to help cure several bacterial, fungal, and parasitic diseases.

Tank Setup

Getting the correct water parameters is more exciting for your marble hatchetfish than for the fishkeeper. So, let’s move on to the more aesthetically pleasing parts of caring for these fascinating fish.


The type of substrate you choose for your marble hatchetfish isn’t crucial for their wellbeing. Since these fish live primarily at the top of the tank, they likely won’t venture down to the bottom.

Therefore, you’re welcome to choose the substrate of your preference. The only requirement is that it’s a smooth kind, on the off chance your marble hatchetfish visits it.

We recommend a dark substrate, as it’ll help showcase your hatchetfish’s marble designs.


Floating decorations that mimic their natural environment are best for marble hatchetfish.

So, driftwood, floating plants, and plants that root at the bottom of the tank and grow to the surface are all excellent options.

While marble hatchetfish appreciate areas of densely decorated spaces for hiding and playing, you should also ensure they have open space on the water’s surface to swim.


Some of the best plants to place in your marble hatchetfish’s tank include:

  • Java moss
  • Dwarf lily
  • Red root floaters
  • Mosaic lily

Your hatchetfish will enjoy racing between the roots of these live plants. Don’t be surprised if they munch on some of them for a snack, too, although these fish are primarily carnivores.


Marble hatchetfish live in dimly lit conditions in the wild, so look to give your fish similar lighting. In their natural habitat, this species encounters dense aquatic plants and land vegetation that shelters the water from the sun.

Nevertheless, offering your marble hatchetfish some lighting is ideal so that these diurnal fish can have a sense of day and night.

With that in mind, purchasing an aquarium light and setting it on dim during daylight hours is ideal.


A robust filter is essential for your marble hatchetfish tank.

Filters work to remove visible waste from the tank in addition to invisible toxins. You should use a multiple-layer filtration system so that you cover biological, mechanical, and, preferably, chemical waste removal.

We encourage you to set a reminder for when you need to clean and replace your filter. Unmaintained or malfunctioning filters are one of the most common triggers of illness in marble hatchetfish.


Installing a heater is a must for your marble hatchetfish. These fish require a higher water temperature than most people set as their house temperature.

Buying an aquarium thermometer at the same time as your heater is a good idea.

You can install the thermometer on the side of your tank, allowing you to easily check the temperature daily to ensure the heater is working well.


In the wild, marble hatchetfish have a primarily carnivorous diet. They will happily eat everything from zooplankton to fruit flies and other insects that hover near the water’s surface.

Try to fill your marble hatchetfish’s belly with high-quality protein sources such as live, frozen, or freeze-dried:

  • Brine shrimp
  • Bloodworms
  • Tubifex worms

When you’re in a rush, it’s also okay to feed your marble hatchetfish high-quality dried fish flakes.

You should feed your marble hatchetfish twice per day, encouraging them to eat their fill of food in two to three minutes. After that time, remove all remaining food.

Using this approach will prevent your hatchetfish from becoming overweight and keep waste in their aquarium to a minimum.


Breeding marble hatchetfish is relatively straightforward, and these fish often lay eggs without prompting. However, the young fry rarely stands a chance, as they typically become snacks for other fish in the tank.

Therefore, it’s best to set up a separate breeding tank.

You can do so by placing your fish in a 15-gallon tank with lots of floating plants, setting the temperature between 76°F and 79°F. As blackwater fish, they’ll do well when the pH stays within 5.5 to 6.5.

Since snails like to eat marble hatchetfish eggs, check to ensure the plants you put in your breeding tank don’t contain these crustaceans.

Then, move two or more marble hatchetfish into the tank and wait for them to spawn. The male will put on a mating ritual by chasing the female around the tank before she releases her eggs, and he fertilizes them.

At that time, remove the parents. Otherwise, they’ll begin eating the eggs.

Within 36 hours, you’ll see baby fry swimming around the tank. Feed them a diet high in small brine shrimp and micro worms until they’re large enough to transfer with larger fish.

Common Diseases

Marble hatchetfish are sensitive, and it’s common for them to fall ill with several diseases that occur in tropical fish tanks. Below is an overview of some of the conditions you may encounter.

Hole-in-the-Head Disease

Hole-in-the-head disease is a condition caused by the protozoan Hexamita. It results in pits appearing in a marble hatchetfish’s face, opening the opportunity for other parasitic and bacterial infections.

Treating hole-in-the-head disease involves giving your fish medicated fish food with metronidazole.

Fin Rot

Fin rot occurs in marble hatchetfish in the form of either a bacterial or fungal infection. It usually appears under poor water conditions.

You’ll need to treat your marble hatchetfish’s water with either an antibacterial or antifungal medicine, plus perform frequent water changes.


Ich is a persistent parasite that causes tiny white specks on marble hatchetfish. The parasite most commonly arrives via an infected tank mate that you introduce into the aquarium.

You’ll want to apply special ich medication to the water, continuing treatment well after the parasite appears to leave.


Lymphocystis is an iridovirus that causes wart-like bumps on marble hatchetfish. It most commonly occurs under poor water conditions.

Currently, there isn’t a treatment for lymphocystis. However, removing the environmental stressors will help prevent the spread of the virus, and marble hatchetfish can often live for a long time with it.

Potential Tank Mates

The ideal tank mates for marble hatchetfish are peaceful fish that are around their same size.

That said, tiger barbs enjoy bothering hatchetfish, and some larger gentle fish may turn your school of hatchetfish into a meal.

So, below are some of the best species to include in your marble hatchetfish tank:

  • Tetras
  • Dwarf cichlids
  • Corydoras

Shellfish like crabs and shrimp are also wonderful tankmates for marble hatchetfish. Since these critters live at the bottom of the tank, they won’t compete for water surface space.