Redhook Myleus

Myleus rubripinnis, the Redhook Myleus, is native to the Amazon and Orinoco river basins and is one of the most visually striking members of the Serrasalminae family. Its deep, laterally compressed silver body and the characteristic red 'hook' of the anal fin make it unmistakable among pacu species. In the wild it inhabits flooded forests and river margins where it feeds on fallen fruit, leaves, and aquatic vegetation.

In the aquarium Myleus rubripinnis requires pristine water quality and very strong filtration to cope with its substantial herbivorous waste load. It grows to around 40 cm and must be provided with a very large aquarium — ideally in excess of 1000 litres — with open swimming space and a bare or sandy substrate. Artificial or robust live plants are needed, as it will consume soft-leaved species rapidly. A tight-fitting lid is essential as it can jump strongly.

Despite its large size it is a peaceful fish that poses no threat to tankmates too large to swallow. It does best in a group of its own kind or alongside other large, peaceful South American fish such as large geophagine cichlids or other pacu species. Regular partial water changes, a varied vegetable-based diet, and subdued lighting help maintain health and colouration.

Water: Soft to moderately hard, pH 5.5–7.5, temperature 24–28°C; excellent filtration essential due to heavy bioload. Tank: Minimum 1000 L with long, unobstructed swimming lanes; robust décor only as plants will be consumed. Feeding: Primarily herbivorous — offer fruit, cucumber, courgette, spinach, and high-quality veggie pellets; supplement with occasional protein. Breeding: Rarely bred in captivity; requires enormous conditioning tanks and seasonal flooding simulation. Compatibility: Peaceful with fish too large to swallow; excellent with other large peaceful SA species but keep away from piranhas.