Help with diagnosis please!


New member
I put my reef to bed Friday night and all was well. Saturday, about 11 or 12 hours later I noticed one of my fish stuck on a powerhead. Then I looked closer to find almost all of my fish dead and on the bottom of my 400 gallon display. I lost several fairy wrasse, a black tang, a powder brown, several anthias and a couple other tangs. About 10 fish or so total. My only survivors are a pair of clown fish and a neon goby.
I have not added anything new to my tank in months. Also, all of my corals are fine, including many acropora. My water parameters also check out in the normal range. I did not lose power. Nothing else seems unusual and the corals are doing fine as are the surviving fish.
I feel really bad as most of my fish were with me for up to several years.
If anyone has any ideas what could have acted so quickly and lethally I would appreciate knowing as I am stumped.
None of the fish were marked except the one in the powerhead. One of the anthias died with its mouth open.
Thanks for any help on what might have happened.


New member
We just had the same thing happen in a 50 gallon tank. The survivors were also the clown fish. I will throw out the details in the reef forum.