Care guide · Freshwater · fish
Common hatchetfish
Gasteropelecus sternicla
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The common hatchetfish, Gasteropelecus sternicla, is a relatively large surface-dwelling member of Gasteropelecidae. It occurs in South American river systems and is sold under inconsistent trade names. Do not confuse it with the silver hatchetfish Gasteropelecus levis or smaller Carnegiella species. Check identification against a complete fish and reliable diagnostic features. This guide covers G. sternicla only. It is a shoaling fish, can be startled by sudden movement and is strongly adapted to life close to the water surface. A quiet setup also helps the whole group feed calmly and retreat under cover when disturbed.
Plan your aquarium →At a glance
- Temperature
- 20–28 °C
- pH
- 5.0–7.5
- GH
- 1–12 °dGH
- Aquarium length
- At least 120 cm
- Minimum aquarium volume
- At least 108 L
- Adult size
- At least 4 cm
- Group size
- At least 6 individuals
- Temperament
- Peaceful
About this species
Seriously Fish reports 40 mm standard length; FishBase gives a maximum near 4 cm standard length and aquarium specimens around 6.5 cm total length. Standard length ends at the base of the tail, whereas total length includes the caudal fin, so these figures need not conflict. Its powerful body and enlarged pectoral fins are associated with jumping and movement near the surface. Adults are larger than the small Carnegiella hatchetfishes.Natural habitat
The species is reported from slow-flowing forest streams, tributaries and swamps in South America, often where surface vegetation is abundant. Floating plants provide cover and can reduce skittishness. Retain open surface space for swimming and feeding. Driftwood and leaf litter can suit an appropriate setup, but the essentials are a spacious, calm swimming area and a secure cover.Aquarium and layout
Seriously Fish recommends a tank base of at least 120 by 30 cm, about 108 litres. Footprint and length matter: a tall tank of the same volume does not provide equivalent surface area. Keep a shoal and fit a strong, tightly sealing lid; startled fish can jump several metres. Cover gaps around cables and filters. Specialist care information recommends groups of six or more; provide more room than the minimum wherever possible.Water conditions
Seriously Fish lists 20–28°C, pH 5.0–7.5 and GH 1–12 dGH. FishBase gives a narrower set of natural/ecological reference values. These are ranges, not a recipe for rapid water adjustment. Keep conditions stable and acclimate fish with regard to their previous water. Measure temperature and chemistry reliably. Avoid large sudden fluctuations even when the final reading falls within a published range.Behaviour and group size
Gasteropelecus sternicla is a shoaling fish that may be flighty and active. Choose peaceful companions that do not constantly compete for food at the surface and are not small enough to become prey. Boisterous or aggressive tankmates can cause chronic stress. Assess adult size, behaviour, swimming zone, shoaling requirements and available tank length. Overlapping temperature or pH values alone do not prove a combination is suitable.Feeding
In nature, the species feeds mainly on insects at or above the water surface, and also takes crustaceans and worms. Offer suitable small live or frozen foods such as Daphnia and bloodworms, along with appropriately sized floating dry foods. Some fish need time to accept dry food. Ensure food does not immediately sink and observe every fish feeding. Vary the diet and remove leftovers; an exclusively sinking diet poorly matches this fish’s feeding zone.Breeding
The sources reviewed do not provide a reliable, detailed routine for breeding this species in a home aquarium. FishBase’s cited account reports that it has not been bred in captivity; this does not prove breeding is impossible, but it does mean a routine or successful method should not be promised. Prioritise a stable shoal, suitable food and a secure lid. Do not transfer breeding methods from other hatchetfishes.Sources & review
This care guide draws on several specialist sources and was last checked on .
View the sources
- Seriously Fish — Gasteropelecus sternicla — aquarium footprint, water, behaviour and feeding
- FishBase — Gasteropelecus sternicla — taxonomy, size, ecology and distribution
- California Academy of Sciences — Eschmeyer’s Catalog of Fishes — valid name and nomenclature
- Aquarist Atlas — Gasteropelecus sternicla — specialist natural history overview