The reason i ask about compatibility, what i am really looking for is aggression and aggression goes hand in hand with breeding. When some fish breed they will kill their mate or any fish in the tank so that is why i ask that. I dont want a fish that breeds really easy but then has to be in a 100 gal tank all by itself because it is way to aggressive. I was asking about fish that breed really easy and i like to know how there aggression is because i stay away from aggressive fish and you have to seperate their fry too so they dont kill each other. Could you have cicilids in with lets say some platies or dwarf gouramis. I guess i should have stated NON aggressive fish that are easy to breed. I understand some fish get aggressive during breeding and thats fine, just not one that is aggressive all the time! I also ask about the fish people mentioned cuz im interested in them. Im not just gonna go out and buy a fish cuz its easy to breed. I like to read and know everything about the fish i go out and get before i get it home. I made that mistake one time with a chinese algae eater that killed almost all my fish, i thought it was a fish that just ate algae but i was wrong on that cuz it killed my birthing platies! I dont want to make that kind of mistake again!