I have tiawan reefs, venustus, and O.B peacocks together and about every 3 to 5 days one of the breed will die. The water test is great everything is normal. They are in a 180 gallon tank with (1) fx5 and (2) whisper 60 hangons on the back. I feed them new life spectrum once and sometimes twice a day. The other night I had a peacock start nose diving and it died that night then 2 nights later I noticed my tiawan reef hidding behind a rock, it was breathing real hard the next morning it was dead also. Please give me some advise.