Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Serrasalmus rhombeus

Black piranha

Black piranha, Serrasalmus rhombeusBlack piranha, Serrasalmus rhombeus
Photos by Andy Rapson


Serrasalmus: Latin, serran, serranus, saw and a fish of genus Serranus + Latin, salmo = salmon

General Notes:

One of the few fish in the hobby which has a VERY SERIOUS BITE. Black piranhas are usually intolerant of all tank mates unless the aquarium is huge, they become increasingly handsome and aggressive with age. Ideally this species should be kept alone in its own tank. Unlike some other piranhas S. rhombeus doesn't form in to large permanent shoals and is more of a solitary fish in by nature.
Some Countries ban the import of this fish due to the risk of them being released and establishing a viable population beyond their normal range. Such a population could do untold damage to the local environment. This can't happen in the UK because of the cold winter temperatures we experience. Like oscars these fish could damage aquarium equipment when adult to avoid this it would be best to set the tank up with an external power filter with an inbuilt heater-stat in order to keep it out of the tank itself. If this isn't possible then using a heater guard is strongly recommended. Black piranhas are relatively slow growing and large specimens can be very expensive.


Wild S. rhombeus prey on other fish for most of their diet when they are big enough, very small ones prey on insects. In captivity use earthworms, prawns, shell fish, and fresh or frozen whole fish such as lancefish, whitebait, sardines ect. Apart from the ethical issues in the UK it is illegal to use live fish or any other live vertebrate as food. Avoid using red meat apart from beef heart as it contains to much animal fat which fish cannot digest.


There are no external differences between the sexes. Neither parent guards the brood after spawning.


Black piranhas have been bred in captivity but not very often because of the difficulty in being able to maintain a pair in the same aquarium even for a short time.

Wild status

S. rhombeus is a widespread species and not under any major threats. All specimens offered for sale will probably be wild caught, this is significant when it comes to their care because generally wild caught fish are less adaptable to changing conditions, poor water quality or the wrong water chemistry.

Information at a glance

pH: 5 - 7
dGH: 3 - 10
Temperature: 22 - 28°C (72 - 82°F)
Diet: Carnivore
Size: 41cm (16in)
Min tank size: 675 litres
Difficulty level: Intermediate
Aquarium type: Specimen
Swimming level: Middle

Distribution and habitat

distribution map for Black piranha, Serrasalmus rhombeus

Origin: South America: Amazon and Orinoco River basins, north and eastern Guiana Shield rivers, and northeastern Brazilian coastal rivers.

Habitat: Found in the rapids but is also captured in deep zones of main rivers


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Serrasalmidae
Genus: Serrasalmus
Species: S. rhombeus

Common name:
Black piranha

Synonyms: Salmo rhombeus, Serrasalmus niger, Serrasalmo immaculatus, Serrasalmo paraense, Serrasalmus paraense, Serrasalmo humeralis gracilior, Serrasalmus boekeri, Serrasalmus normani, Pygocentrus normani