Black Pacu

Colossoma macropomum is the largest member of the Serrasalmidae, reaching 100 cm and 30 kg in the wild. Juveniles are strikingly dark with scattered silver scale highlights, making them popular in the trade, but adult size requirements are frequently underestimated. It is a commercially important food fish across South America and is widely farmed.

Despite its impressive piranha relatives, C. macropomum is a peaceful herbivore and frugivore, using its powerful molar-like teeth to crush seeds and hard fruits that fall into flooded forests. In captivity it is active, responsive to its keeper, and long-lived — but truly enormous facilities are non-negotiable.

Often mislabelled as a 'Pacu' alongside Piaractus brachypomus in the trade.

Water: 24-30°C, pH 6.0-7.5, moderately soft to moderately hard; robust biological filtration essential given the large bioload of adults. Tank: Minimum 2000L for a single adult; public aquarium displays or custom-built systems are the appropriate home for long-term care. Feeding: Omnivore; fruits, vegetables, pellets, occasional whole fish or prawns; varied plant-based diet is essential for long-term health. Breeding: Achieved in aquaculture via hormonal induction; not feasible in home aquaria. Compatibility: Peaceful with similarly sized fish; the primary concern is size — juveniles will quickly outgrow any home aquarium.