a lot of fish live with p's in nature but it's not nature we are talking about here, it's in a fish tank. wolf fish in nature eats piranhas as well, of course size dependent. if you value your fish then you wouldn't put anything that could harm it together with them. there are member cohab wolf fish and caribes together in a 300g and it's been working for 8 or 9 months. it can be done but you gotta know what you are doing and be prepare that there will be lose, sooner or later, just matter of time.