I would like to breed some agressive fish that could live in a 55 or 65g tank. What type would thrive in this size tank and be more agressive than other fish?
a 65 is usually like a tall 55, right? I think a salvini pair would be perfect. They only get about 8 inches max, and females are smaller. I don't think anything much larger than that should be bred in a 55, at least not if it is full grown.
Salvini are aggressive and really awesome looking.