Blackwing hatchetfish

Carnegiella marthae

Also known as Marthae Hatchetfish

FreshwaterFish

Care at a glance

Temperature
68–82°F
20–28°C
pH
5.5–7.0
Adult size
1.4 in
3.5 cm
Minimum tank
30 gal
115 L
Temperament
Peaceful
Social behavior
Shoaling
Swim level
Top
Difficulty
Medium
Breeding
No record
Rarity
Very rare
Family
Gasteropelecidae
Origin
Venezuela, Brazil

Overview

Keep at least six together in a tank of roughly 115 liters with plenty of surface area, and always use a tight lid. They sit right at the top and eat from the surface, so offer floating flake, small frozen foods, and live items like fruit flies or mosquito larvae. Keep them warm in the mid 20s C with soft, acidic to neutral water. They're peaceful and best with calm tankmates.

In the wild

Blackwing hatchetfish live in slow tributaries and floodplain pools of the Amazon, mostly in Brazil and Venezuela. The water is soft, acidic, and stained dark with tannins, with floating plants and roots up top where these fish stay. They want surface cover and very still water, so floating plants and a gentle filter outflow help a lot.

Good to know

This is a small hatchetfish in the family Gasteropelecidae, reaching about 3.5 cm. The deep, keel-shaped chest houses the muscles that power its oversized pectoral fins. Captive breeding is rarely recorded. The IUCN lists it as Least Concern.

Did you know

Hatchetfish are true flyers, not gliders. They beat those wing-like pectoral fins fast enough to break the surface and travel a short distance through the air, usually to escape something chasing them. That's exactly why a lid is non-negotiable.

Weekly picks

Tank mates

Blackwing hatchetfish is a peaceful, shoaling species that keeps to the top. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a Blackwing hatchetfish need?

A Blackwing hatchetfish needs at least 30 gal (115 L). It spends most of its time in the top.

What temperature and pH does a Blackwing hatchetfish need?

A Blackwing hatchetfish is comfortable at 68–82°F (20–28°C) with a pH of 5.5–7.0.

How big does a Blackwing hatchetfish get?

An adult Blackwing hatchetfish reaches about 1.4 in (3.5 cm).

Does a Blackwing hatchetfish need a group?

Yes. A Blackwing hatchetfish is a shoaling species and should be kept in a group, not singly.

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