Hot Water Fish

Ax fish

  • Scientific name: Carnegiella Strigata
  • Common name: Marbled ax fish, breast, marbled breast, black-finned breast
  • Aquarium size: 50 to 70 liters
  • Temperament: Very peaceful
  • Temperature: 25ºC (between 23ºC and 28ºC)
  • pH: 5.5 to 6.5
  • Diet: Carnivore
  • Length: 4cm


The one commonly known as ax fish (Carnegiella strigata) , is actually the maximum exponent of the genus Carnegiella, of the Gasteropelécidos family , known as ax fish.

They are known as ax fish, due to their special morphology, which resembles the shape of an ax.
It is a very sociable, gregarious and calm fish, suitable for any small community aquarium. With an aquarium of 50 liters to 70 liters it is more than enough for a small school.

One of their most peculiar characteristics is that they are very good swimmers and «jumpers», they are able to «fly» almost literally great distances.

It is not a difficult fish to keep in the aquarium, althoughThey are sensitive to white spot disease , so measures must be taken to prevent it from appearing.


The hatchet fish is rather small, measuring about 4 centimeters long, although for the aquarium you must remember that it is a gregarious species, and that they need the company of more congeners of the same species.

Its body is laterally compressed, with a parallel back. Its chest area is gracefully bulging, creating that ax shape that gives them their name and is so peculiar.
They do not have an adipose fin, and their dorsal fin is located very close to the tail fin.

Its pectoral fins are elongated with highly developed muscles, which allow it to jump out of the water and glide. In this way they are able to travel great distances.


It is called a “marble” ax fish because its body is lined with dark colored spots, which alternate with others of lighter colors.

The dominant tones are green and yellow, the spots are usually pink and silver tones.
It has a characteristic yellow horizontal line, which is usually present in a common way in all specimens. The line runs from your eye to the caudal pendulum.

Sexual dimorphism

The differences between males and females are not very obvious.

They are distinguished mainly because the female Ax Fish has a more bulky and rounded abdomen than in the male specimens.

Although its reproduction in the aquarium is not very common, it is also more evident that we are dealing with a female, if she is pregnant and carries her eggs.

Distribution and habitat

The ax fish is widely distributed throughout South America, although the Carnegiella Strigata or marble ax fish is native to Peru .

He likes the slow channels of rivers and lagoons, where he finds areas with densely planted banks.

Aquarium conditions

The aquarium for the Ax Fish should be medium in size, about 50 to 80 liters , preferably elongated (rectangular), since it is a very swimming fish.

It must be covered, due to its propensity to jump . They are fish that like to swim very close to the surface.

As for the water conditions, they should move in the following parameters:

  • Temperature: Between 23ºC and 28ºC
  • Hardness: Up to 15º
  • pH: Between 5.5 and 6.5

The aquarium must be very planted, with a lot of floating vegetation, to reproduce its natural habitat.


They are fundamentally carnivorous fish in nature , they feed on insects and larvae that they capture on the surface.

They can also prey on fingerlings. If we keep them in a community aquarium you must take this into account, since they can eat the young of other fish.

In the aquarium we can provide you with a diet based on good quality dry food , which we must supplement with live food (if possible) such as brine shrimp or mosquito larvae.

Dry foods should be designed to stay on the surface, like flakes. The moment they go to the bottom, they will no longer eat them.


The Ax Fish is gregarious and peaceful, likes to swim in a small group of its same peers. Ideally a group of 5 to 6 individuals should be kept.

They like to swim very close to the surface, so they can share space with fish that prefer the intermediate or lower areas of the aquarium.

Ax Fish compatibility

With these fish they are compatible without any type of restriction:


The reproduction of the axfish is not known in much detail, and it is not easy for it to occur spontaneously in the aquarium.

In order to be successful in the hatchfish breeding, we must procure a breeding aquarium , with about 40 liters.

First, we will take a couple of ax fish. We will lower the lighting, in addition to adding peat to stain the water and lower the pH .

We will add a good amount of live prey.

It is oviparous, although it does not make a specific nest. Spawning is done freely, the eggs are scattered between the vegetation and the substrate.

After laying, the eggs usually hatch after 30 hours.The fry usually feed on plankton as soon as they are born, later we must add brine shrimp nauplii .

After laying, the parents are usually removed, so that the eggs and the young are not eaten.

Photographs and images of the Ax Fish

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