The common hatchetfish (Gasteropelecus sternicla), also known as the river hatchetfish, and the silver hatchetfish, is a freshwater fish with a uniquely shaped body. However, the name silver hatchetfish is actually a misnomer, and should be used instead to describe Gasteropelecus levis. The name hatchetfish originates from its laterally compressed body, which resembles the head of a hatchet.
Common hatchetfish are native to South America, and can be found in Peru, Venezuela, Guyana, Suriname and French Guiana. These fish are mainly found in heavily vegetated, slow-moving streams, and swamps, though they can also sometimes be found in larger bodies of water.
Much of their time is spent near the surface of the water, and they are capable of leaping distances of up to 9 feet (3 metres) out of the water to escape predators. Though they are only capable of performing these jumping feats once or twice, without requiring a significant period of rest. They also regularly jump out of the water to catch flying insects, but these jumps are usually only over fairly short distances.
These fish stay relatively small in the home aquarium, and grow to around 2.5 inches (6.5cm) in length. The average lifespan is about 5 years, though with an exceptionally well cared for fish, lifespans as long as 7 years have been reported.
Common hatchetfish require an aquarium that is at least 20 gallons (75 litres), though a larger tank is usually preferable, since it allows for a larger group to be kept. These fish are a schooling species, and should be kept in groups of at least 6, but seem to remain healthier and more active in groups of 8 or more.
Any aquarium containing these fish should be heavily planted, and floating plants seem to reduce their escape attempts and skittishness in general. Some easy to care for floating plants to add to their aquarium are Amazon frogbit, water lettuce, and duckweed. Beyond plants, their tanks should also contain driftwood or bogwood, and the addition of leaf litter to the bottom helps to recreate their natural environment.
Common hatchetfish are an excellent choice for a community fish tank, and while they are known to fight among themselves, they rarely direct their aggression at other fish. Their tank mates should be other small, non-aggressive fish – preferably mid-tank or bottom dwellers – such as corydoras catfish, or some of the more peaceful tetras.
An aquarium containing common hatchetfish must be covered, as these fish are notorious jumpers. If the lid of their fish tank isn’t completely sealed, odds are you’ll quickly lose some fish as they leap to their deaths.
When choosing a filter, the best choice is usually a hang-on-back filter. Not only is it economical, but they are among the most effective filters on the market. One of the best filters to choose is the Aquaclear Power Filter, and this filter is both rugged, and reliable. I have been using these filters on most of my tanks for well over a decade with no major issues.
These fish are primarily carnivores in the wild, and their diet is mainly composed of insects, worms, and crustaceans. Most will readily take to eating prepared foods in the aquarium, and one of the best foods to offer them is Hikari Tropical Micro Pellets, which provides for all of their nutritional requirements.
However, if at first they refuse to accept prepared foods, their food can be mixed in with feedings of live or frozen foods, until they more readily accept it. This may take time, but they should eventually take to the prepared foods.
Because of their carnivorous nature, their diet should contain regular feedings of live or frozen foods. The best live foods are mosquito larvae (illegal to cultivate in some areas), daphnia, black worms, and wingless fruit flies. Their tastes remain similar in frozen foods, and blood worms, brine shrimp, daphnia, and blackworms are all excellent foods to feed them.
Females are generally more round-bodied than males – especially when egg laden. But outside of body shape, they can be a difficult fish to sex.
Common hatchetfish are egg layers, but very little is known about triggering breeding in the home aquarium, and at this time there are no reliable guides to breeding them.