Black Piranha

Serrasalmus rhombeus is the giant of the piranha world, reaching 45 cm or more and packing the most powerful bite relative to body size of any living fish. Juveniles are beautifully patterned with large dark spots on a silver body, but adults darken dramatically to near-black with age, hence the common name.

Unlike Pygocentrus, S. rhombeus is a solitary ambush predator and must be housed alone or risk catastrophic aggression toward any tankmate. It is capable of biting through steel mesh and even aquarium glass when stressed, making enclosure integrity paramount. Feeding requires care to avoid injury to the keeper.

Ownership is heavily restricted across Europe, North America, and Australia; thorough legal due diligence is mandatory before purchase.

Water: 24-28°C, pH 5.0-7.0, soft water strongly preferred (1-8 dGH); blackwater tannin supplementation beneficial for comfort and colour. Tank: Minimum 500L for a single adult; heavy-duty external filtration; minimal décor with one large cave or root; thick acrylic or reinforced glass recommended. Feeding: Strict carnivore; large whole prawns, fish fillets, silversides; use long feeding tongs — never hand-feed; feed every 2-3 days. Breeding: Not achieved in home aquaria; solitary nature makes pairing extremely dangerous. Compatibility: Must be kept alone; do not attempt to house with any other fish; verify legal status in your region before purchase — restricted or banned in many countries.