The most aggressive freshwater fish in the world?

[cockroach]

If we are talking total damage done, the list has a few of the brutes.
If we are talkin' pound-for-pound, A-hole ornery. A mature red-tailed black shark, Epalzeorhynchos bicolor, is an absolute hazard for many tank mates.

 

[neoprodigy]

my money is on the aimara, thing would chase me outta its tank... i think an xl rhom would bite you if one tried to pick it up, otherwise its a chicken

this!