Silver Hatchetfish (Gasteropelecus sternicla)

The Silver Hatchetfish (Gasteropelecus sternicla) is one of the most distinctive freshwater fish in the hobby, with its dramatically deep, compressed, keel-shaped body that resembles a hatchet head. Native to slow-moving rivers, forest streams, and flooded areas throughout much of South America (particularly the Amazon and Orinoco basins), it is a true surface-dwelling species that rarely ventures far below the surface film.

Hatchetfish are specialized surface hunters that feed on small insects and invertebrates that fall onto or are found near the water surface. Their large, wing-like pectoral fins allow them to leap out of the water to escape predators — in the aquarium, this means a tight-fitting, well-sealed lid is absolutely essential, as they are among the most proficient jumpers of all aquarium fish.

Silver Hatchetfish are schooling fish that should be kept in groups of 8 or more. In adequate groups in a well-maintained aquarium with floating plants and a calm surface, they display natural surface-level schooling behavior and are more relaxed. Solitary specimens or small groups become stressed.

They prefer soft, slightly acidic water and benefit from gentle surface agitation. They are peaceful with all fish that occupy lower water levels and are ideal companions for mid-water and bottom-dwelling South American species.

Water Parameters: Soft, slightly acidic water: pH 5.5–7.0, temperature 23–28°C, GH 1–10. Tannin-stained water from driftwood and Indian almond leaves is beneficial. Maintain gentle surface movement for oxygenation. Stability is important — avoid abrupt parameter changes.

Tank Setup: Minimum 80 liters for a school of 8. TIGHT-FITTING LID IS MANDATORY — they are exceptional jumpers. A surface layer of floating plants (water lettuce, frogbit) provides security, reduces light stress, and mimics natural conditions. Open surface swimming area alongside floating plant cover is ideal.

Feeding: Surface-feeders that prefer floating foods: high-quality micro flake food, floating micro pellets, freeze-dried or live small insects (fruit flies, baby crickets), and frozen blood worm at the surface. Train them to the surface by placing food at the waterline. Feed twice daily.

Tankmates: Peaceful with all fish that don't occupy the surface zone. Ideal companions for Cardinal Tetras, Corydoras, small cichlids, and other South American species. Avoid fish that compete for the surface or that might jump at the hatchetfish.

Health: Sensitive to poor water quality. Maintain soft, acidic conditions with weekly 25% water changes. Can stress easily — keep in appropriate groups with a secure, covered tank. Watch for ich and bacterial infections.