But if you raise the midas in the tank by his self, and then down the line plunk in some more fish, more often than not they will wind up badly hurt. I have seen normaly fairly doscile fish like JD's and Oscars relentlesly attack Dovii's and Jags almost twice their size due to this. My lfs had a 7" female jd that claimed an entire 180g for herself due to the fact she was the lone inhabitant for months, she wouldnt let anything else live in that tank. they removed her later and placed her in a 90g with several other cichlids and she was fine. so there are tons of different factors. way to vague of a question IMO!