Home / Fishes / Tetras, piranhas and pacus / Common hatchetfish
No federal permit to keepCommon hatchetfish
Gasteropelecus sternicla
Fishes › Tetras, piranhas and pacus (Characiformes) › Gasteropelecidae (Freshwater hatchetfish)
The common hatchetfish or river hatchetfish (Gasteropelecus sternicla) is a species of freshwater ray-finned fish belonging to the family Gasteropelecidae, the freshwater hatchetfish.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 1.5 in / 3.9 cm).
- Water: Freshwater.
- Temperature: 73–81°F (range recorded for this species).
- pH: 6–7.
- Hardness: 0–15 dGH.
- Layout: An open-water swimmer: needs long, open swimming space with few obstacles.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. FishBase classes it as a carnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 47 × 12 in (roughly 29 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–82 °F, pH 5–7.5, 1–12 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more; suited to a community tank.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Cover a good portion of the water surface with floating plants, which will help to make this flighty species less skittish.”
- Diet: “Naturally feeds on insects on and probably above the surface, crustaceans, worms.”
- Tankmates: “Very peaceful but it can be nervous and shy, and will not compete well with boisterous species for food.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Freshwater hatchetfish
Applies to most species in this group. Habitat: These South American surface fishes inhabit forest streams, tributaries and swamps with surface vegetation, with marbled hatchetfish associated particularly with blackwater and flooded forest. [fg245-sternicla, fg245-strigata]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Fit a very tight cover: startled hatchetfish can jump out.
- For Carnegiella strigata, provide at least 75 × 30 cm (30 × 12 inches) of surface area.
- For Gasteropelecus sternicla, the cited minimum surface area is 120 × 30 cm (48 × 12 inches).
- Provide floating plant patches and planted cover around surface swimming space.
- Use gentle to moderate current; for C. strigata, maintain soft water within the cited 1–10 dGH and pH 4.0–7.0 ranges.
Climate & lighting
| Water | 68–82.4°F |
Diet
- Gut-loaded small fruit flies offered at the surface.
- Small live or frozen Daphnia.
- Artemia nauplii for small Carnegiella.
- Frozen bloodworms and suitably sized dry foods once accepted.
Social life
- Keep at least six G. sternicla; C. strigata does best with ten or more. Choose similarly peaceful companions that do not outcompete them for food.
Health watch
- Ammonia-related illness.
- Nutritional deficiencies.
- Introduced parasitic skin or gill infections.
Understanding the animal
About this animal
About this animal
This fish occurs in South America where it is found in the drainage basins of the Amazon, Orinoco, Essequibo, Tocantins-Araguaia, Mearim, upper Paraguay river basins, and in the coastal drainages in Guianas. It has been recorded from Bolivia.
Quoted from the Wikipedia article “Common hatchetfish” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams. Gregarious, can sometimes be aggressive or calm. Frequents slow-flowing waters of creeks and swamps. |
| Water it lives in | Freshwater, 73–81 °F (23–27 °C), pH 6–7, hardness 15 dH. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
What this means for care
- Keep water within its wild range, 73–81 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 89°F (up to 92°F in the hottest sampled areas) |
| Cool-season lows | about 69°F (down to 62°F in the coldest sampled areas) |
| Average temperature | 77–80°F across sampled records |
| Relative humidity | 78–84% on average (driest month about 76%) |
| Rainfall | about 2236 mm a year |
Measured at 255 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The common hatchetfish or river hatchetfish (Gasteropelecus sternicla) is a species of freshwater ray-finned fish belonging to the family Gasteropelecidae, the freshwater hatchetfish. This fish occurs in South America where it is found in the drainage basins of the Amazon, Orinoco, Essequibo, Tocantins-Araguaia, Mearim, upper Paraguay river basins, and in the coastal drainages in Guianas. It has been recorded from Bolivia. Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Trinidad. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Wild diet | The hatchet fish has a diet which is composed primarilly of insects and larvae. — Animal Diversity Web |
| Behavior | G. sternicla is not an aggressive fish. — Animal Diversity Web |
| Reproduction | Research has shown that Gasteropelecus sternicla only breed for a short period coinciding with the start of the rainy season. — Animal Diversity Web |
| Appearance and size | Female Gasteropelecus sternicla are known to reach a maximum length of about 49 millimeters (mm), while their male counterparts reach a maximum of about 42 mm. — Animal Diversity Web |
| Biology | Gregarious, can sometimes be aggressive or calm. Frequents slow-flowing waters of creeks and swamps. Lives in groups at the surface. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 47 × 12 in (about 29 US gallons).
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish: Carnegiella strigata Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Gasteropelecus sternicla Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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