Arnold's Myloplus

Myloplus arnoldi is a large pacu belonging to the closely related genus Myloplus, which was separated from Myleus based on morphological and genetic evidence. Like its relatives it is a deep-bodied, laterally compressed herbivore from South American river systems, attaining sizes that can reach or exceed 38 cm in large aquariums. Its silver body displays subtle iridescence and it develops a more robust build with maturity.

Care requirements are similar to those of Myleus species: very large aquarium (minimum 1000 litres), powerful filtration, soft to moderately hard water, and a plant-based diet. The species is active and benefits from strong water movement across open swimming lanes. It will consume any soft-leaved aquatic plants and should be housed in an unplanted or artificially planted aquarium.

Myloplus arnoldi is peaceful with other large fish and may be housed alongside other Myloplus or Myleus species, large geophagines, or peaceful cichlids of comparable size. It is not suitable for community setups with smaller fish. Regular feeding with cucumber, courgette, and specialised herbivore pellets ensures continued health and the impressive growth this species is capable of.

Water: Soft to moderately hard, pH 5.5–7.5, 24–28°C; very high filtration capacity needed. Tank: 1000 L minimum; open swimming lanes; unplanted or artificial décor only. Feeding: Plant-based diet essential — vegetables, fruits, algae wafers, and large herbivore pellets. Breeding: No captive breeding records available. Compatibility: Peaceful with other large non-aggressive species; avoid housing with piranhas.