Black Piranha

Geographical Origin and Habitat: This species is widely distributed throughout the Amazon and Orinoco river basins, as well as coastal rivers of the Guianas in South America. It occupies a diverse range of freshwater habitats, including deep main river channels, flooded forests (igapó), and fast-flowing tributaries.

Taxonomy and Morphology: Belongs to the class Actinopterygii, order Characiformes, family Serrasalmidae, and genus Serrasalmus. Known as the Redeye Piranha, it features a distinctive laterally compressed rhomboid body shape, a powerful underslung jaw, and razor-sharp, triangular teeth.

Social Behavior: An extremely territorial and solitary predator. Unlike Pygocentrus piranhas, it does not form schools and exhibits intense intraspecific aggression. They will attack, mutilate, or consume any other fish in the enclosure, making them unsuitable for community tanks.

Coloration and Sexual Dimorphism: Juveniles are silvery with dark spots. As they mature, the body color darkens, eventually turning a deep charcoal grey or jet black in old specimens. The eyes develop a striking, intense ruby-red color. There is no visible sexual dimorphism between males and females.

Aquarium Setup: Requires a very large aquarium of at least 300-400 liters (80-100 gallons) for a single adult. The layout should include large driftwood roots, smooth rocks, and robust plants to provide shade. A secure, heavy lid is mandatory, along with a powerful external filtration system.

Diet and Feeding: Strictly carnivorous. Feed a varied diet of fresh or frozen fish fillets (such as trout or silversides), whole shrimp, mussels, and earthworms. Avoid feeding live feeder fish from stores, as they frequently carry pathogens and parasites that can infect the piranha.

Water Quality: Prefers soft, slightly acidic conditions: pH 6.0-7.2, water hardness (GH) 5-12 dGH, and temperature 24°C-28°C (75°F-82°F). Due to the high amount of waste produced by their meaty diet, large weekly water changes of 30% to 40% and strong filtration are required.

Compatibility and Cohabitation: Must be housed alone in a single-specimen aquarium. Do not attempt to keep with other fish, invertebrates, or conspecifics. Any tankmates will eventually be hunted and killed, as this species is an uncompromising solitary predator.

Aquarium Breeding: Breeding in home aquaria is exceptionally rare and poorly documented due to the extreme aggression between specimens. In nature, temporary pairs form to spawn in nests dug into the substrate, followed by fierce parental protection of the eggs.

Risks and Diseases: Prone to fungal skin infections and bacterial diseases if water parameters deteriorate. A significant risk is physical injury to the aquarist; their bite can cause severe lacerations. Use extreme caution during maintenance and never put hands near the fish.