In my experience...clown loaches do better with a semi aggressive environment. However in a larger tank ie 100 or 125 you can mix semi and community if you do it carefully. I would recommend lots of places for the loaches to hide. Some combinations that I like, fishwise, are schooling fish, maybe some tiger barbs or green tiger barbs, some tetras, whatever varieties you like and maybe a mated pair or two of swordtails. I'm not sure what your price range is for fish, but larger Discus are also nice and contract well to clown loaches.
But this is all just an opinion...I'm more of a saltwater girl
