I set up a 150 gallon planted tank this summer with the interest of making it a discus aquarium. Last week I bought a discus (2") and he has been doing fine. Today, I bought two more, one that's the same size and one that's 1.5". Unfortunately, the one that I had first has been nipping and attacking the other two. Since it's such a large tank, I would normally think that the discus would be able to hide, but it's been brutal. There are about 20 other fish in the tank, including roseline barbs, clown loach, and rams. I have a 10 gallon quarantine. Not sure what to do... I want to be able to keep all 3 together successfully and add to the group by getting more discus, but I dont want any more discus to be attacked by the current aggressor.