Marbled Hatchetfish Care Guide - Aquarium Setup, Diet & Breeding

The Marbled Hatchetfish is a small, distinctive characin named for its deep, hatchet-shaped body. Its silver-brown flanks are marked with irregular dark marbling, while a dark line and subtle golden or bronze tones may show along the body depending on the light. The enlarged pectoral muscles and unusually deep chest give the species its characteristic angular profile.

These fish spend most of their time just beneath the surface, where their upturned mouths are suited to taking insects and other small prey from the water’s top layer. They are peaceful, alert and highly social, becoming most confident when kept in a good-sized group.

Like other hatchetfish, Carnegiella strigata is an exceptional jumper. It can launch from the water when startled, using its powerful pectoral muscles to skim briefly across the surface. This behaviour is thought to help it escape predators in the wild.

In nature, Marbled Hatchetfish inhabit quiet rainforest waters surrounded by overhanging vegetation, fallen leaves and submerged branches. Their subdued colours provide camouflage among the broken shadows and reflections at the surface, while their streamlined shape allows quick escapes from danger.

Marbled Hatchetfish come from slow-moving forest streams, flooded forest and tributaries across the upper and central Amazon Basin in South America, including parts of Brazil, Peru and Colombia. They are closely associated with shaded, tannin-stained blackwater habitats and the surface of the water.

A group should have at least 75 litres, with a tank measuring about 90 cm long by 30 cm wide or larger to provide swimming space and a broad surface area. Use a secure, tightly fitted lid because these powerful jumpers can clear surprisingly small gaps. A dark sand or fine-gravel substrate, subdued lighting, floating plants, overhanging vegetation and driftwood create the shaded surface habitat they prefer. Gentle filtration and some open water beneath the plants allow the group to swim naturally without excessive turbulence.

Up to about 4.5 cm (1.8 in) in total length. Females are generally slightly larger and deeper-bodied than males, particularly when carrying eggs.

In the wild, Marbled Hatchetfish feed mainly on small insects, insect larvae and other tiny organisms collected from the water’s surface. In captivity they accept floating flakes and micro-pellets, but their diet should be varied with live or frozen foods such as fruit flies, mosquito larvae, daphnia and brine shrimp. Offer small portions that remain at the surface, as these fish are not well suited to competing for sinking food.

Marbled Hatchetfish suit peaceful community aquariums with similarly calm, small fish such as neon tetras, cardinal tetras, pencilfish, small rasboras, peaceful Corydoras and otocinclus catfish. They should not be housed with large, aggressive or boisterous species, fin-nippers, or fish that compete intensely at the surface. Their delicate fins and surface-dwelling habits make them poor companions for predatory fish and highly active tankmates.

Marbled Hatchetfish are egg scatterers and are challenging to breed in the home aquarium. A separate, mature breeding tank with very soft, acidic water, subdued lighting and fine-leaved or floating plants can encourage spawning. The adults scatter their eggs among vegetation, after which they should be removed because they may eat the eggs. The eggs usually hatch within around 30 to 36 hours, and the tiny fry require infusoria or another suitably fine first food before they can accept larger foods.

Females are usually a little larger and fuller through the abdomen than males, while males tend to remain slimmer. The difference is subtle, and sexing young Marbled Hatchetfish can be difficult until the fish are mature.