Spotted hatchetfish

Geographic Origin and Biotope: Widespread from Central America (Panama) to South America (Colombia, Venezuela). Inhabits slow lakes, quiet river oxbows and flooded forest areas with abundant floating vegetation and slightly turbid waters.

Taxonomy and Morphology: Spotted Hatchetfish (Gasteropelecidae family). Hyper-compressed body laterally and monstrously protruding ventral keel (half-moon or axe shape), which houses powerful pectoral muscles for flight. Length 6-7 cm (2.5 inches).

Social Behavior: Absolutely gregarious and peaceful; lives its entire existence flattened against the surface of the water. Terrified by sudden movements, it reacts with lightning-fast sprints jumping out of the water, "flying" flapping its pectoral fins to escape predators.

Coloration and Sexual Dimorphism: Brilliant silvery body with an opaque olive green back to blend in. The flanks are studded with characteristic rows of black and brown spots, which distinguish it from other hatchetfish. No visually evident sexual dimorphism.

Aquarium Setup: Heavy and totally airtight glass lid MANDATORY (will jump out even from the slits for the tubes). Calm tank with floating plants (Pistia, Limnobium) under which it can take shelter, while still leaving ample free swimming areas on the surface.

Diet and Feeding: Very strict surface insectivore. The mouth is turned totally upwards: it will ignore any food that sinks. Feed with fruit flies (Drosophila), high quality floating flakes and freeze-dried bloodworms/brine shrimp.

Water Quality: Requires soft and slightly acidic water (pH 6.0 - 7.0, GH 2-12). Temperature 24-28°C (75-82°F). Being confined to the surface, it is hypersensitive to the too strong currents created by the filter outlet and to bacterial biofilms on the water surface.

Compatibility and Tankmates: Perfect for quiet Amazonian community tanks. Cohabits beautifully with peaceful Tetras (Cardinals, Rummy-nose), Corydoras, Apistogramma and Loricariids. Do not combine with voracious Cichlids or competitive surface fish (like Zebra Danios).

Aquarium Reproduction: Rare and poorly documented event in the amateur field. Courtships involve long jumps out of the water and the eggs are scattered among the roots of floating plants (e.g. Water Hyacinth). The fry is extremely minute.

Risks and Diseases: Death from traumatic impacts or lethal jumps (on the floor or stuck in the lamps) is the cause of death of 95% of the specimens. Highly prone to Ich (White spot) if the aquarium is subjected to cold surface drafts when opening the lid.