Royal Knifefish

Gymnotus javari is a large, deep-bodied gymnotid knifefish native to the upper Amazon basin tributaries of Peru and Brazil. Its dark, laterally compressed body and imposing size make it one of the most impressive gymnotiform species. Like other Gymnotus species it produces pulse-type electric organ discharges and is a nocturnal hunter of invertebrates and small fish. It can be highly aggressive toward conspecifics and other knifefish. Rarely exported; specimens available in the trade represent a significant commitment for the keeper. Pristine, warm, soft water and generous hiding spaces are essential for long-term health.

Water: 24-29°C, pH 6.0-7.2, soft and slightly acidic; excellent filtration and oxygenation. Tank: Minimum 500L; large PVC pipes or hollow logs; fine sand; low lighting. Feeding: Carnivore; earthworms, large bloodworms, prawns, small whole fish; primarily nocturnal feeder. Breeding: Not documented in captivity; presumed seasonal egg-layer in nature. Compatibility: Solo or with very large, robust fish; highly aggressive toward conspecifics.