These are the only diseases I have ever encountered while keeping piranhas. Remember, before treating your fish for any disease remove the carbon first. If you dont then the medication will be absorbed into the carbon. Always follow the instructions on the medication to be used.

"Ich"- Small white cysts on the fins and body of the fish. The fish will also try and scratch itself against rocks, gravel and other decor. This is a protozoan and can be treated with readily available medications from your local fish store.

"Fin and Tail Rot"- I have encountered this disease with my more delicate wimple piranha. This disease shows up as clouding on the edges of the fins, and progresses to severely frayed and even destroyed fins. This disease should be treated immediatly with a broad spectrum nontoxic antibiotic. This medication is also readily available at your local fish store.

If you properly care for your piranhas, diseases would rarely show up. Most diseases can easily be prevented from the start: When buying feeder fish for your piranha, select only feeders that are healthy looking and active, avoid lethargic feeders that look very sickly. Always quarantine new fish before introducing them to your main tank.