|Red-Belly Piranha Juvenile. Auditor and a Gentleman Photo.|
In spite of the small size at which they are purchased (usually on the order of about three inches), these fish can reach 13 inches in length with a weight of about 8 pounds. Close relatives of tetras, they do best in groups - a group of 4-5 can be kept comfortably through adulthood in a 70 gallon tank, though this tank would likely have to be a species tank, as these fish are carnivorous.
The terrible reputation of the red-bellied piranha for violence is overstated - even large ones are more likely to swim away from a human intruding on the tank than to attack them. Having said that, it is preferred to feed them live food wherever possible. I feed an alternating pattern of live insects and frozen blood worm, though it is possible to keep them plenty healthy on a diet of predator sticks. Resist the urge to feed such as mice or larger fish as neither, kept as pets, are nutritionally balanced for these animals.
|Adult of the same species. Wikipedia Commons.|
These fish have a terrible reputation that is largely unearned. Though oft-feared, they are just as docile a pet as any snake, reptile, or rodent I've ever handled, and more docile than quite a few of the latter - hamsters spring to mind.