Right now in my 55 are 25 lemon tetras i plan on also adding 15 corys, not sure on species yet. So the question is how many angels? Will more then one possibly form a pair and kill off the rest of the tank? as for filtration i have a magnum 350 with 2 large biowheels and the canister is full of bioballs and then a penguin 330 biowheel