Black-Winged Hatchetfish (Carnegiella Marthae)

Since most species of fish inhabit the lower and middle levels of the aquarium, aquarists looking for a distinctively shaped fish to incorporate into a community tank with other fish of similar size and temperament will like the black-winged hatchetfish.

Origin & Habitat

Black-winged hatchetfish are a freshwater species of fish endemic to Venezuela and Brazil in South America. There have also been reports of them inhabiting Colombia’s Rio Vichada and the Rio Inrida rivers, which are tributaries of the Orinoco river.

They are prevalent in the upper Orinoco River basins in Amazonia and the Cao Quiribana stream in Venezuela. While also commonly found in Brazil’s Rio Negro drainage, the second-largest tributary of the Amazon River and the largest blackwater river in the world, and are occasionally found in Madeira River, which empties into the Amazon River downriver.

This species only inhabits black-water rivers, streams, and swamp forests, which are surrounded by dense riverside flora that is typically overhanging, resulting in a substrate frequently covered in fallen branches, tree roots, and leaf litter. Due to an abundance of decomposing organic matter, the waters are acidic, soft, and frequently stained brown.

Black-Winged Hatchetfish Care

Black-winged hatchetfish are capable of leaping out of the water with great velocity, and they frequently use this ability to catch flying insects in the wild. Because of this, aquariums should have tight-fitting lids to prevent the fish from jumping out of the aquarium; however, this is more likely to occur during the night or if they are startled.

This species is rather sensitive to high levels of hardness, alkalinity, and poor water quality; prolonged exposure may very well result in significant mortality rates.

Since black-winged hatchetfish spend the majority of their time at or near the surface, they should ideally be maintained in a densely planted environment, particularly with floating plants, and tall plants where they will typically gather.

Black-Winged Hatchetfish Diet & Feeding

Black-winged hatchetfish are largely considered to be insectivorous fish, eating a range of terrestrial and aquatic insects. The large pectoral fins on this species of fish also allow them to spring out of the water quickly to catch flies.

In fact, a recent study was conducted to discover the degree of their insect predatory nature and the proportion of insects in their diet. According to the study, they had a very well-balanced diet, which included the following:

• 11% – adult mayflies
• 11% – adult true flies and larva
• 11% – lake fly larva
• 11% – beetles
• 11% – fish scales
• 22% – plant matter
• 22% – other insects

Their diet in an aquarium should be comparable in that it is well-balanced and made up of foods with insect-based ingredients. Because they frequently congregate at the top of the water column rather than diving to the bottom, it is better to offer them food that floats, whether they are dry, frozen, or live sources.

Excellent live or frozen sources of food to incorporate into their diet include artemia, daphnia, moina, and microworms. Tubifex and high-quality flake food prepared from insect larvae are also readily accepted.

Tank Mates & Temperament

As a peaceful shoaling fish species, black-winged hatchetfish should be kept in groups of at least 8 to 10 to minimize their naturally cautious disposition. In larger shoals, they’ll become more active, less skittish, and also display more vibrant colors.

Ideal tank mates for the black-winged hatchetfish are species that are of similar size with a peaceful temperament. Some suitable community members include angelfish, barbs, rasboras, danios, dwarf cichlids, tetras, discus, livebearers, corydoras, catfish, plecos, and labyrinth fish species that are peaceful in nature.

Mildy aggressive bottom-dwelling fish are acceptable since they will rarely come into contact with the black-winged hatchetfish who inhabit the top of the tank. It’s not advisable to keep some species of tetras and barbs with excessive activity levels that are regarded as semi-aggressive. Since there are very few places to hide inside aquariums, large, energetic species could also put them under too much stress.

Male & Female Differences

When they have been conditioned on a healthy diet, adult black-winged hatchetfish are translucent enough to clearly see the female’s eggs during spawning seasons. Females may appear to be larger in width when they have produced many eggs, yet the size difference is often negligible. It is impossible to identify sexual dimorphism between males and females in younger specimens.

Breeding & Spawning

In the wild, black-winged hatchetfish are a non-guarding, egg-scattering species of fish that typically lays their eggs onto fine-leaved plants.

However, there are currently no recorded instances of them breeding within an aquarium. This is likely related to seasonal changes in their natural environment, rainy seasons can cause water levels to rise by 15 meters and they temporarily migrate into flood plains during this time.

More Information

In 1927, American ichthyologist George Myers gave this fish the name C. marthae in honor of his first wife.

Contrary to what many people think, black-winged hatchetfish are not considered to be flying fish. In 1995, Wiest employed high-speed video photography to show that the pectoral fins are only used to exit the water and not when it is airborne. The behavior is essentially a modified threat response or used to feed on flying insects, and a forceful jump would be a better description.

Additionally, Wiest also observed that the fish appeared to be capable of only jumping once or twice before needing a break because of the amount of energy required to move its large pectoral fins.

The smallest hatchetfish species are those found in the genus Carnegiella. There are presently four recognized species of Carnegiella, each of which is smaller and devoid of an adipose fin (C. Marthae, C. Schereri, C. Strigata, and C. Myersi).

To distinguish each species of Carnegiella from one another, the easiest method would be to identify the markings on their body:

• Black-winged hatchetfish (C. Marthae) have inconsistent dotted-like streaks.
• Pygmy hatchetfish (C. Myersi) is the most translucent in appearance with small dots usually located on their underside.
• Silver hatchetfish (C. Schereri) are the most silver in appearance with a few larger dots near their dorsal fin and little to no faded dots on their underside.
• Marbled hatchetfish (C. Strigata) are easily identified by its marbles appearance.