Giant Pacu Myleus

Myleus pacu is one of the more imposing members of its genus, capable of exceeding 45 cm in optimal conditions. Found across the Amazon and Orinoco drainages, it inhabits flooded forests and large river channels where it consumes prodigious quantities of plant material, fruits, and seeds. Its large, disc-like silver body, combined with powerful musculature, makes it one of the most impressive herbivorous fish available to specialist aquarists.

Keeping Myleus pacu well requires a truly enormous aquarium — a minimum of 1500 litres — with industrial-grade filtration capable of handling its heavy waste output. The tank should feature a deep fine-sand substrate, robust driftwood, and no live plants. Water must be soft to moderately hard, warm, and changed frequently. A secure, weighted lid prevents the powerful jumps this species is known for.

Despite its size Myleus pacu is not aggressive and coexists well with other very large, peaceful fish. It is not suitable for community aquariums and is a specialist fish requiring significant financial and space investment. Diet should be predominantly plant-based, supplemented with high-quality large herbivore pellets. This species is best kept as a long-term project by dedicated advanced aquarists.

Water: Soft to moderately hard, pH 5.5–7.5, 24–28°C; industrial filtration essential for very heavy bioload. Tank: 1500 L absolute minimum; unplanted except for very tough species; open mid-water lanes needed. Feeding: Heavy herbivore diet — large fruit, vegetables, algae wafers, large sinking pellets; feed generously. Breeding: No viable captive breeding records; not feasible in home aquaria. Compatibility: Peaceful with other very large fish; incompatible with piranha or aggressive large cichlids.