Black Winged Hatchetfish

Black Winged Hatchetfish (Carnegiella marthae) is a remarkable freshwater fish with one of the most extraordinary body shapes in the aquarium hobby. The enormously enlarged, keel-shaped chest — formed by massive pectoral muscles that account for up to a quarter of the fish's total body weight — powers genuine flight above the water surface to escape predators. The Black Winged Hatchetfish is the most dramatic of the small Carnegiella — the pectoral fins are distinctly dark to black-edged, creating the 'black wing' effect as the fish hovers near the surface. The silver body has a cleaner profile than the marbled species, making the dark fin edging the defining feature. Carnegiella — black-edged pectoral fins are the defining feature.

Feeding & Care Tip: Sera Vipan Tropical Flakes make an excellent surface staple for hatchetfish — floating flakes suit their surface-feeding behavior perfectly. Hikari Micro Pellets are also accepted at the surface. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Baby Brine Shrimp fed at the surface before it sinks, and Hikari Frozen Daphnia. Feed small amounts multiple times daily — hatchetfish have small stomachs and do best with frequent small meals rather than one large daily feeding.

⚠ Tight-Fitting Lid Essential: Hatchetfish are genuine fliers — the enormous pectoral muscles that give them their deep keel-shaped chest power actual leaps out of the water to escape predators. This is not a tendency to jump; it is a physical ability unique among freshwater fish. Any gap in the lid will result in fish on the floor. A fully sealed lid with only the minimum opening for equipment is required.

Native to slow-moving, heavily shaded forest streams, pools, and flooded forest areas of the Amazon and Orinoco basins — blackwater environments with very soft, slightly acidic, tannin-stained water. The aquarium should replicate these conditions: soft, slightly acidic water, tannin additions from Indian almond leaves or driftwood, floating plants to provide the essential surface cover this species needs, and subdued lighting. A mature, stable aquarium is important — freshly imported Carnegiella are sensitive but become hardy once established.

Keep in groups of at least eight — hatchetfish are genuinely schooling fish that are stressed and prone to disease in small numbers. They occupy exclusively the top 2–3 inches of the aquarium, leaving all lower zones free for other species. Ideal tankmates include small tetras, pencilfish, Corydoras, and small rasboras that inhabit lower water zones. Avoid any fish that disturbs the surface zone.

Hatchetfish are strict surface feeders — they will not descend to take food from the mid-water or substrate. All food must be offered at the surface or just below it. Floating flake food and pellets work well; frozen foods should be fed near the surface before they sink. Any food that sinks past the top few inches of the water column will not be eaten by the hatchetfish.

Care & Ideal Parameters