Scientific Name: Pygocentrus nattereri
Breeding Strategy: Nest builder
Ease of Breeding: Moderate with captive bred specimens, difficult with wild-collected individuals.
Introduction: Despite their fierce reputation, piranhas make fascinating aquarium residents and are generally well mannered as long as their keepers take a few precautions- giving them plenty to eat, and never sticking their bare fingers in the tank without knowing where the piranhas are in relation to your fingers! Also, it is important to know that it is illegal to keep piranhas in some states so be sure to check your local and state regulations before purchasing them. Red-bellied Piranhas are mature enough to breed when they are about 6 inches in size.
Sex Differences: Can be difficult to distinguish, especially in juveniles. Mature males tend to be darker than females, who have a more yellow tinge, but the difference is so subtle that it may not be apparent to an inexperienced eye. Many breeders buy groups of six or eight and let them pair off naturally.
Water Conditions: Hardness and pH not critical, but piranhas like temperatures in the 77 to 80 degrees F range.
Equipment: Piranhas can be bred in a species aquarium, or the pair can be placed in a breeding tank. For the latter, use a tank that is a minimum of 50 gallons; 100 gallons would be better. Add a canister or power filter and substrate such as fine gravel for a nest site. Floating plants may help the fish feel more secure.
Conditioning and Triggers: Allow fish to pair off from the school naturally; you will know when they have done so because they will select a territory and begin chasing other fish away; they will also darken in color, becoming a purpleish black. Condition on feeder fish and chunks of meat. Some breeders say raising the temperature slightly, to about 82 degrees F, may trigger spawning; others say that lowering the water in the tank, then using fresh water to raise it again gradually, will also have the same result.
Spawning: The male will begin shifting gravel around, building a nest, while the female watches. When he is done, he will urge her toward the nesting site, and she will help him to put the final touches on it. When ready to spawn, they will circle each other, then begin swimming side by side. Heads pointing toward the substrate, they begin to release eggs and sperm, sometimes nipping and slapping at each other with their tails. The process is repeated numerous times until all eggs have been released, something that can take hours. Afterward the male usually guards the eggs, fiercely protecting them from tankmates who get too close. It is not neccessary to remove the female.
Brood Size: Between 500 and 1,500.
Fry care: the male will fan his fins to keep oxygenated water circulating over the orangey-colored eggs, which will hatch in about two days and become free swimming about a week later. It is best to remove the fry to a seperate tank (a 20 gallon tank will be large enough at first) eitherbefore they hatch or immediately afterward. Keep water circulating with a pump and airstone. Feed with baby brine shrimp; later you can add ground cichlid pellets, blood worms, and commercial fry food.