I dunno 'bout ya'll, but my money is definitely on this Tanganyikan resident,
Endemic to Lake Tanganyika (and certainly other parts of Africa), Crocodylus niloticus, (Nile Crocodile) is not recommended for keeping by the inexperienced aquarium keeper - nor for actual keeping in aquariums, at all! :roll:
But, if you just HAVE to keep the 'Most Aggressive' Tang.....
A long-time staple of C-f, these (Who's toughest? Meanest?) things have always cracked me up.
In nature, something will always dominate (or just eat) something else. And yes, for my own Tanganyikan BIG BAD I put up? I'm sure there is almost certainly a species of microscopic bacteria or possibly a virus, that would just - EAT THAT BAD BOY ALIVE.