Gasteropelecus sternicla
Common Hatchetfish
Classification
Gasteropelecidae
Distribution
Guyana, French Guiana, Venezuela, Peru.
Habitat
Slow-moving forest streams, tributaries and swamps. The fish are most often found in areas with an abundance of surface vegetation.
Maximum Standard Length
Around 2.6″ (6.5cm).
Aquarium SizeTop ↑
24″ x 15″ x 12″ (60cm x 37.5cm x 30cm) – 27 litres.
Maintenance
Cover a good portion of the water surface with floating plants, which will help to make this flighty species less skittish. Other decor isn’t particularly critical, but it looks good in both heavily planted setups and Amazon biotope tanks, with driftwood branches, a sand substrate and some leaf litter. Make sure the tank cover is very tightly fitting, as it’s capable of clearing several metres in a single jump.
Water Conditions
Temperature: 73-81°F (23-27°C)
pH: 6.0-7.0
Hardness: 2-12°H
Diet
Sometimes a little reluctant to take dried foods initially, but it will usually learn to accept them over time. A large proportion of the diet should consist of frozen and live foods, such as bloodworm and daphnia. Gut-loaded Drosophila fruit flies make an excellent food if they’re available.
Behaviour and CompatibilityTop ↑
Very peaceful but it can be nervous and shy and will not compete well with boisterous species for food. Good tankmates include other small fish that inhabit different parts of the tank, such as tetras, dwarf cichlids and catfish such as Corydoras and Loricariids. Always buy at least half a dozen, as it won’t settle without the security of conspecifics.
Sexual Dimorphism
Females are noticeably rounder-bodied than males when full of eggs.
Reproduction
Unknown. Probably breeds in a similar fashion to the marbled hatchetfish, Carnegiella strigata.
NotesTop ↑
This species spends almost all of its time at the water surface, although it will sometimes retreat into midwater if threatened or feeding. Like other freshwater hatchetfish, it’s renowned for its ability to fly for distances of several metres. This behaviour is used both to catch flying insects, and to escape potential predators.
As well as giving rise to the common name, the strange shape of the fish is thought to be involved in the ‘take-off’ and ‘landing’ phases of flight, the trenchant belly stabilising the fish at it exits and re-enters the water. It also has specialised fins. The pectorals are enlarged and have massive muscles attached to them, and the pelvics are reduced. The pectoral fins are actually beaten in a similar way to the wings of birds or insects during flight, and an audible buzzing sound can often be heard as the fish moves through the air. The hatchetfish are the only known family of fish to employ powered flight, as opposed to the gliding behaviour seen in the marine flying fish.
G. sternicla is generally considered to be the hardiest hatchetfish available in the hobby, but it can still be quite delicate when initially imported. Once acclimatised, it proves to be a very good aquarium resident. It’s often confused with the silver hatchet, G. levis, and is often labelled as such when on sale.
