I have a 40g long with a about 7 lithobate yellow blaze at 4-5" 1 male and about 6 females in with a trio of Aul. maleri island at 3.5"-4". They get along great but some times the lithobate tries to stop/eat the eggs when the maleri's breed but the maleri always succeeds. At first I put them together temporarily but it worked out so well I kept them together.
I also have a 55g with 6 Ps. Flavus, 6 Ps. Red Top Ndumbi, 3 Borleyi Red Fin, and 4 Hap. sp. 44 Red Top all adults. Its overstocked but they are doing great, they show absolutely no aggression towards each other. But I do plan on taking at least on of the groups out, prolly the 3 Borleyi Red Fin.
My show tank, which is really just left over breeder males all around 5". There is a red empress, a Aul. Mozambque Cobue, Aul. Ngara Flametail, Aul. Maleri Island, and a one eyed Lithobate yellow blaze. They also get along great. I did used to have a second flametail which fought constantly with the other flametail to the point where I had to get rid of one. If I didn't I'm sure one would have ended up dead.
I my experience when you have a all male tank just don't kept two of the same species that look the same or are the same, i.e. a Aul. Benga with a Aul. Maleri Island. and if I am breeding I always put fish that are a different color and far from a different species like a peacock with a hap, to lower the chance of interbreeding.
I have some pics of some of these setups in my fish room post .
http://www.monsterfishkeepers.com/forums/showthread.php?p=2268809#post2268809