I currently have a 40 breeder w ten yellowtail and two domino damsels , one coral beauty and three black mollies, NO LIVE ROCK, plastic plants,, NO skimmerstwo 110 aquaclears w biomedia and polyfilter, no water changes in three months, Fish get along very little aggression, no staking out territories and thye fish eat like pigs and are healthy. I did this as an experiment after keepiong reefs for twenty yrs w all the live rock, skimmers, sumps, ETC ETC. So it works think of aquarium store tanks, sparsely decortaed and fish in numbers,the tank has been set since july this year not one loss. The water is crystal clear and the fish show no sign of stress or problems, maybe not what we have been told or taught but truth be told after all the bells and whistles I could not be more pleased w results and the ease of and lack of major Financial expenditure, knowledge and patince is the key. Maybe not for everybody but it works!