Just a few observations and considerations1) Fish have personalities they also have different space requirements. That is " how much elbow room they need" varies also.
2) A couple of clues I have noticed is that if a fish becomes territorial young even if it means just hanging out in a corner alone be careful in whom you tank him with.
3) Fish of the same type may not get along as well as they they do with others. Ex Green terror hangs with my oscars but will not tolerate another Green Terror. So watch your fish
4) over crowding can lead to aggression and stress simply changing tank set up can do wonders. Anything that stresses your fish can lead to aggression so basic principals diet, decorations, water quality etc.
5) African and south american chiclids generally do not do well together learned this one the hard way.
6) have had better luck by populating tank with fish that would/could normally en counter each other in the wild.
This is a fun hobby enjoy it just use some common sense and watch your fish as they grow the clues are there just have to know what your observing.
K
