How to Raise a Piranha

Piranhas can seem cute when they're small and hiding among tank decorations much of the day, but they don't stay small. Depending on the species, adult piranha can be 12 to 16 inches long. They come from river environments and live best in large tanks -- a 100-gallon tank suits a single adult piranha; add 20 gallons for each additional piranha. Red-bellied piranhas tend to school in the wild, so you can likely keep a few in the same tank, although they might attack each other at some point. If you're keeping a black piranha as a pet, house him alone -- he's just as likely to eat another piranha as the dinner you provide him.

Piranhas aren't strictly carnivores, although meat is definitely their meal of choice. If you have aquatic plants in your tank, you might see your fish take a few bites here and there. They also eat fish pellets and flakes occasionally, and they can benefit from the vitamin boost these foods provide. But for most of their meals, plan on feeding protein such as krill, mealworms, earthworms or feeder fish. Unless you raise your own under controlled conditions, thaw frozen versions of these foods or buy live ones from reputable fish food suppliers. Avoid grabbing insects and worms from your yard -- they might have ingested chemicals such as pesticides and herbicides, which they can transfer to your piranha. Juvenile fish need to be fed up to four times per day, while sub-adults usually need food about twice a day. Feed mature adults about once every two days.

Piranhas can survive in a variety of tank conditions, but they prefer a water temperature of between 78 and 82 degrees Fahrenheit and a sandy substrate. Juveniles are especially fond of aquatic plants. In the wild, they spend much of their time hiding from predators until they reach their adult sizes. However, adults enjoy swimming among the plants as well. They also like large pieces of driftwood that offer secluded places to rest.

Before buying a piranha for a pet, check with your local and state regulations. Many states ban piranhas because people sometimes release them into the wild; introducing non-native species can wreak havoc on your local environment. Non-native species can compete with indigenous ones for food, sometimes endangering the other species' survival. Also, state governments often don't want to risk local fisherman catching piranhas unexpectedly and potentially becoming injured. Even if you have no intention of releasing a pet piranha, always follow local regulations.

Owning a piranha means taking a few precautions to ensure he doesn't decide your hand looks tasty for dinner. Even small, a piranha has razor-sharp teeth that can easily bite through your skin; as an adult, he can bite through bone to remove entire fingers. To prevent injury to yourself, never dip your hand in the water to feed a piranha. Also, don't place a hand with a wound, even a small scratch, in or near the top of the water -- the blood might attract the piranha, who swims powerfully enough to jump out of the water. Clean the tank with long tools instead of putting your arm inside, and use a net to catch your fish when it's necessary to move him. He can bite through the net, so don't stabilize him with your hand. Instead, hold a second net under the first to catch the fish if he bites a hole in the first net and falls through.