Red-finned Myloplus

Myloplus rubripinnis is closely related to the Redhook Myleus but belongs to the now-separated genus Myloplus following recent taxonomic revision. It displays striking vivid red colouration on the anal, caudal, and often pectoral fins that contrasts dramatically with the silver body. Native to South American river systems, it can reach 38 cm and is considered one of the more visually spectacular members of the pacu group.

Care requirements are demanding: at minimum a 1000-litre aquarium, heavy-duty filtration, soft to moderately hard water, and consistent warm temperatures. Like all members of the serrasalmid family it is a vigorous feeder that produces substantial waste, and water quality must be carefully maintained through frequent partial changes. Live plants will be consumed and should be substituted with artificial alternatives.

Myloplus rubripinnis is peaceful and does well with other large, non-aggressive South American fish. Its bold red fins make it one of the more photogenic pacu species and it is a popular choice with specialist aquarists and public aquarium curators. A herbivore-focused diet with quality pellets, fresh vegetables, and occasional fruit is essential for maintaining the vivid fin colouration.

Water: Soft to moderately hard, pH 5.5–7.5, 24–28°C; high-quality filtration with frequent large changes. Tank: 1000 L minimum; open mid-water; artificial plants; strong lighting to show off red fins. Feeding: Herbivore diet — vegetables, fruit, spirulina pellets; red-enhancing foods help maintain vivid colour. Breeding: No captive breeding documented. Compatibility: Peaceful with large non-aggressive fish; excellent display species.