How to Breed Piranha

Piranhas are freshwater fish native to South America with a reputation for ferocity. While aquarium owners must take care not to house piranhas with other kinds of fish, piranhas pose little risk to people. Breeding them requires a large aquarium and careful attention to water temperature, lighting and water quality. Owning piranhas is illegal in some states and requires permits in others due to concerns that these aggressive fish could end up in the wild. Be sure to check state law in your area.

Things You'll Need

  • Large aquarium, 100 gallons or more
  • Small aquarium, 10 to 15 gallons
  • Aquarium heaters for each tank
  • Under-gravel filters for each tank
Show More

Instructions

    • 1

      Acquire a large aquarium, ideally 100 gallons or more. Larger tanks are better if you are keeping several piranhas in the same aquarium, as a breeding pair will become aggressive to other piranhas once it begins mating.

    • 2

      If using a separate aquarium for breeding, single out a breeding pair from among your piranhas by selecting a thick fish and a thinner one to put in the breeding aquarium. Size isn't a guarantee of sex in piranhas, but female piranhas are generally thicker than males. The red-bellied piranha, or Pygocentrus nattereri, is the species most likely to breed in captivity.

    • 3

      Install a heater that will maintain a temperature of 73 to 83 degrees Fahrenheit. Piranhas produce a great deal of waste, so you'll need a high-quality filter to maintain the clean water conditions that piranhas prefer for breeding. Light the aquarium with regular fluorescent lights, arranging lighting so that half of the tank is darker than the other.

    • 4

      Prepare the piranhas for breeding by simulating the conditions of the South American rainy season, which is when piranhas breed in the wild. Frequent, large water changes sometimes trigger breeding in aquarium piranhas.You'll know your fish are getting ready when their color darkens and they start searching out protected places in the aquarium for laying eggs. Some may start picking up gravel in their mouths and moving it around.

    • 5

      Minimize disturbances for your piranhas once you know they're preparing to breed. The female will dig a small pit in the gravel and lay anywhere from 700 to 4,000 eggs, which will hatch in two to three days.

    • 6

      Once the eggs hatch, transfer the fry to a small aquarium -- 10 to 15 gallons -- filled with water from the parent piranhas' aquarium and fitted with a heater and under-gravel filter. Watch out for aggressive behavior in the adult fish as you transfer the young piranhas. After the fry absorb their yolk sacks, begin feeding them brine shrimp.