If you're looking for a docile fish, get a goldfish. The black piranha (Serrasalmus rhombeus) has a ferocious reputation, and for good reason: with his razor-sharp teeth, extraordinary jaws and lightening-quick movements, his bites can cause serious injury. Powerful jaw muscles allow the black piranha to chomp down with a force equal to 30 times his bodyweight, according to the Daily Mail website. Initially, your piranha might act wildly, play dead or bash into the tank walls, but he should calm down quickly. With the potential to live up to 25 years, he has plenty of time to become comfortable in the tank.
Black piranhas can grow more than 12 inches long, so a full-grown adult requires a tank no less than 100 gallons with plenty of open swimming area. Ensure that the tank has a tight-fitting lid to prevent the piranha from using his powerful body to escape. To help your black piranha feel at home, use a sandy substrate and decorate his tank with floating plants, large rocks and and pieces of bogwood. Despite his fierce reputation, the black piranha has a timid disposition and requires hiding places to feel secure -- install some driftwood roots and branches so he can take cover when needed, for example. Maintain a water temperature between 72 and 82 degrees Fahrenheit.
Pass the Meat and Hold the Veggies
Mostly carnivorous in the wild, the black piranha prefers to dine on the flesh of other species, including insects, fish and crustacean. In captivity, your piranha will happily consume fresh, live or thawed meaty food. Feed him chunks of fish fillets, whole mussels, prawns, chopped squid, chicken pieces and earthworms. When your piranha reaches adulthood, he only needs to be fed two to three times per week. In some cases, your piranha might initially go on a hunger strike until he becomes used to his new home. If he continues to shun food while acclimating to his aquarium, leave some food in the tank with the lights off, which should lead him to begin eating. Remove any leftover food to prevent bacterial contamination of his tank.
All By Myself
If you house your black piranha with other fish, they'll likely become his lunch rather than his friends. Piranhas will swiftly dive toward anything in their environment that resembles food. For this reason, keep your piranha without companionship in his tank. Black piranhas also behave aggressively toward members of their own species and view each other as a potential next meal. They're often wary of each other, and housing them together only adds to their anxiety and skittishness, according to the Michigan State University website. While snails might not make the most thrilling companions, the black piranha typically leaves them alone.
Biting the Hand That Feeds Him
It typically takes awhile for black piranhas to become used to life in captivity, so don't be alarmed if yours initially behaves anxiously. Over time, your piranha will become comfortable in his tank and behave more relaxed around you. Always take extreme caution around the fish, however. Avoid putting your hand in the aquarium for any reason, especially during feeding time. When feeding the piranha, hold your hand at a safe distance above the tank, drop the food inside then tightly close the lid. If the black piranha feels threatened or anxious, he can still lash out with a nasty bite, causing serious injury.