Hey, Jordan, here's your triggers!
Breeding black PiranhaThe black piranha (S. rhombeus) is hard to breed in captivity due to their aggressiveness towards each other. The species has been breed in public and private aquariums that are large enough to house several adult specimens without them causing damage to each other due to the aggression. Black piranhas can be breed in home aquariums but will most likely require an aquarium of at least 2000 L / 500 gallon and perhaps twice that size.
The black piranha breeding aquarium should be densely planted with plants such as Vallisneria, Cryptocoryn., Aponogeton and Echinodorus.
You will need to give your black piranhas a varied diet to get them into spawning condition. Recommended water values are in some degree related to which river in the Amazon your black piranhas originate from but pH 6 and 24-28C / 75-82 F can be used to breed most strains. The water should be very soft to breed this species. Rain season simulation helps trigger the fish to spawn. The eggs are laid in pits in the sand and are protected by the parents.
Black piranha eggs hatch after approximately 2-3 days. The fry is best feed very small food such as infusoria during the first days and then newly hatched brine shrimp.
Hopefully that'll be somewhat helpful in condition any males you may find. The website for referance!! http://www.aquaticcommunity.com/predatory/blackpiranha.phphttp://www.aquaticcommunity.com/predatory/blackpiranha.phphttp://www.aquaticcommunity.com/predatory/blackpiranha.php