Humpback Sabretooth Tetra

Cynodon gibbus is one of the more visually striking members of the Cynodontidae family, combining a pronounced dorsal hump — the 'gibbous' feature for which it is named — with the family's characteristic elongated, curved lower jaw fangs. It reaches around 30 cm and inhabits the mid-water layers of large rivers in the Amazon and Orinoco basins, where it strikes at schools of smaller fish with its formidable dentition.

In the aquarium, Cynodon gibbus requires a minimum 600-litre setup with excellent oxygenation, soft to moderately hard water, and powerful filtration. Its dorsal hump becomes increasingly prominent with age and in well-fed adults it is genuinely dramatic. It is strictly piscivorous and will consume any fish of remotely swallowable size; tankmates must be carefully selected or avoided altogether.

Feeding follows the pattern of other cynodontids: live fish initially, gradually weaned onto fresh whole fish and large meaty preparations. It is more robust than Hydrolycus species in terms of water quality tolerance and is somewhat more feasible for experienced specialist aquarists. Its hump-backed profile and impressive fangs make it one of the most distinctive large characins in the hobby.

Water: Soft to moderately hard, pH 5.5–7.5, 24–28°C; strong oxygenation; good filtration. Tank: 600 L minimum; open mid-water; some large driftwood; secure lid. Feeding: Piscivore — whole fish, fresh fish fillet; wean gradually from live prey. Breeding: Not documented. Compatibility: Aggressive apex piscivore; no small tankmates; best solo.