I have one beautiful turquoise discus in my tank. Yesterday I added 2 more. They are quite a bit smaller & my turk is definitely dominant. They don't dare venture out of their corner or he chases them back. I have live plants, but they are small yet. I added alot of plastic. Maybe it did a bit. I notice the little ones are a bit braver & are venturing further from their corner, but they are still chased back if they are spotted. He really watches them carefully @ feeding time. They don't get much to eat. As I said, mine is a planted tank & should have 12 hours of light / day, but today it got 10 1/2. I figured the little ones deserved a break. Can you think of anything else I could try ? Thanks. Oceansurf.