You really shouldn’t keep anything with piranhas. There is nothing they are “afraid” to attack, it’s just whether they feel like exerting the energy to do so. People have kept plecos, pacu, and some small fast fish (tetras, tiger barbs, giant danios) without incident, but in the same breath others have had their’s all eaten. It’s like one of those things “Nothing has gone wrong until it does.” Haha.
