Used to have five angel fish in my tank a coral beauty, bi-colour angel, a flame angel, koran and a blue angelfish of different sizes with no problems whatsoever. My tank size is 100 gallons at present but used to be only 60 gallons and i still had no problems with all these fish. I lost my flame angel, koran and blue angel due to a horrible outbreak of many diseases. i now just have the bi clour and coral beauty and they are still the best of buds.