Red Bellied Piraha (Serrasalmus Nattereri)
It may be very estrange for some that the dreaded Piranhas are from the same family as small and harmless neons (neon tetra) or Cardinals (P. axelrodi), but the truth is they are morphologically not so distant species.
They are found in South America, Amazon basin, Paraguay-Parana river basins, coastal rivers in north eastern Brazil and Essequibo River (Guyana).
The first thing that catches the attention of this species is a prominent jaw and a powerful mouth full of teeth in terminal position. The dorsal fin is located further back than normal, and anal fin is separated from the flow only by the caudal peduncle. There are important differences between juveniles and adults, both in form and colour (it is a species in which the difference between young and mature specimens is very pronounced).
The dorsal fin lacks spines and has 16-18 rays. The anal fin, also spineless, has 27 to 30 radios.
The silver grey body has large dark spots and the lower part of its body, from the capping to the anal fin is red. In young specimens are appreciable numerous black spots.