Elongated Piranha, Pike Piranha, S. Pingke.
Lakes, ponds and rivers in the Llanos (Venezuela/Columbia), and Amazonian Brazil.
The most remarkable feature of this species is its elongated body, setting it apart from all of its relatives. It's torpedo-like body shape is a clue to its behaviour: this species is a very active and agile swimmer and hunter.
There are at least two different color variants of S. Elongatus: one has a silvery body, with a dark tail fin, humeral spot and facial markings, and greyish dorsal and anal fins. The other variant has a darker face and fins, orange to red pectoral fins, and traces of red in the lower face and gill plates. These variants live in habitats ranging from fast-flowing rivers to ponds and lakes with little water movement. This may suggest the existence of two or more seperate (sub-)species, but it still has to be validated scientifically. The differences in appearance can also be caused be differences in habitat, the water chemistry (black water vs. white water), or diet.
(Serrasalmus Elongatus must be kept by themselves in their own tank. They are so aggressive they will follow your finger from outside the tank. They will eat everything that is offered to them and will usually eat it as it falls in the water. Although not one of the most colorful piranhas, in my oppinion the Elongatus is the most aggressive of the piranha species.)
By: Jonas Hansel (Thank You for the great information)