Blackwing Hatchetfish (Carnegiella Marthae)

Freshwater Blackwing Hatchetfish – Quick Care & Keeping Guide

Blackwing Hatchetfish (Carnegiella Marthae)

Blackwing Hatchetfish (Carnegiella Marthae)

Although I personally find the Marbled Hatchetfish (C. strigata) more attractive, I decided to write about the Blackwing first. The reason is that the Blackwings are even better suited for life in aquaria than the marbled.


They are far less likely to jump when startled than any of their relatives. Also, they are not prone to aggression within their school as marbles.


Blackwings are easy to distinguish from other hatchet fish by the black line that outlines their particular body shape. Their “wings” –actually their pectoral fins– are not always black when you first buy them, but they will get some shading in them once they are out of the store’s display tank and they are kept in a properly decorated tank.

Tank Setup

Now, just because I said these fish are unlikely to jump when startled, does not mean that you can leave their tank uncovered. They are clearly a surface fish and are more than capable of leaping out of tanks.

It was thought that the hatchets actually flapped their pectoral fins to extend their aerial leaps while hunting clouds of insects over the water but recently high-speed photography has disproved this theory.

Floating plants discourage jumping and for Blackwings, floating plants are essential for their long-term care.

Unlike many other hatchet fish, they do not inhabit rivers with a lot of open space. They live in slow-moving waters that are often heavy with surface growth. In the rainy season, the move into the flooded forests and tend to congregate where there are a lot of vegetation and branches.

Tank Size

They need to be kept in groups. Try to buy a least 10 if you can. A group that size can be kept in a 20 gallon/75 liter tank. They make the perfect companion fish for many South American dwarf cichlids (NOT African cichlids no matter how small!)

Quick Overview

  • Origin: Venezuela to Columbia and Brazil
  • Size: 4cm/ 1.5 inches
  • Temperature: 20-28°C/ 68-80°F


They will eat flake food but should also be given high protein, insect-based food like bloodworms, mosquito larvae and fruit flies.


These hatchets like a well-planted tank. When they feel nervous, they dive down into the vegetation. They do not have a preference when it comes to a substrate but keep water movement to a minimum.


No hatchet fish has been bred in captivity. They probably breed at the height of the rainy season when the forest is flooded. To be successful in an aquarium probably requires months of simulating of the dry and wet seasons. It is easy to tell females from males by their larger size, so if someone is up for a long project, it might be possible.

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3 thoughts on “Freshwater Blackwing Hatchetfish – Quick Care & Keeping Guide

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