This thread was posted in 2012, but seeing as it's been bumped up ......
Why don't we ever see any threads asking; Is my tank too big for my fish?
While I agree with Stanzz to a certain extent, the reality is that many of these male cichlids do not pair for life, so forcing them to do so in a confined space, which pretty much all aquariums are, IMO is far more cruel/unfair/whatever, as allowing them to grow out on their own. I have a male midas that flies solo, not by choice, but due to the fact that he has chased to near death and/or killed every other fish that he has been kept with, which started with his own siblings at 3-4" in size. That was in a 6ft tank - he just doesn't mix well with any other fish, period.
Years ago I got rid of a midevil because of his hyper dominant aggression, something that I have always regretted. I later came to realize that some male fish simply need to be kept by themselves, which certainly doesn't mean that they will live out a life with no mental stimulation. My midas is set up across from one of my community tanks, so he interacts with them all day long, just from a place where he can't sink his teeth into any of them. He also has myself and others in the house to interact with, along with a dog toy kept in his tank that he bites & pushes around when he's really worked up.
So while I agree with bigger being better, I do not agree in forcing all fish to do things that would seldom be seen in nature, such as being forced to share a confined space for life.