Blackwing Hatchetfish Breeding Guide

Breeding of Carnegiella marthae is unrecorded in aquaria. This tiny surface-dwelling hatchetfish needs soft acidic water and a tightly sealed cover.

Overview

Carnegiella marthae is a tiny freshwater hatchetfish from the upper Orinoco drainage in Venezuela and the rio Negro drainage in Amazonian Brazil. The largest officially recorded specimen measured 28.1 mm (Seriously Fish). It is a surface-dwelling micropredator. Members of the family Gasteropelecidae have powerful pectoral-fin muscles that let them leave the water surface, so a tightly sealed cover is essential (Wikipedia).

Sexing

Seriously Fish notes that some specimens grow larger and become rounder-bodied than others, presumably representing adult females, but reliable sexing methods are not described.

Conditioning

The species feeds on small invertebrates and zooplankton at the surface; in the aquarium it should receive regular small live and frozen foods such as Artemia nauplii, Daphnia, Moina and grindal worm. Documented parameters are 20-28 C, pH 4.0-7.0 and hardness 18-179 ppm (Seriously Fish). It is gregarious and best kept in groups of ten or more, which is the recommended husbandry baseline for any breeding attempt.

Common Challenges

The lack of reliable sexing, the absence of any documented spawning trigger, and the fish's small size and timidity make breeding extremely difficult, and no success has been reported.