I read on the net about how you can make a soup from the Pacu's head, because of the high fat content and the chemicals contained within the fat it slows the release of oxygenated red blood cells to the brain resulting in a semi-concious drowsy type trip.
Apparently the amazons rave about it.
I am considering tripping on pacu soup soon cos I have the same problem (why do I always buy fish in pairs?)
BTW - Do not release any fish into the wild.