I have about five recently acclimated discus in a 90 gallon tank (Amm 0, nitrite 0, nitrate 0-5, ph 6.5, gh 3). I didn't put them in altogether and I'm thinking that may have been a mistake, since the first one I put in has been bullying the rest. Only that one will eat and acts calm, but the others are constantly hiding and breathing hard whenever I turn the lights on.

Any ideas on what I can do?