Whats going on here? 2 Anthias dead, 1 Tang slowly dying

[jimrawr]

Welp... tang is dead.. I think the FW dip was harsh for him. I made sure the water was correct temperature, aerated with an airstone and mixed it vigorously before putting him in. He stopped moving completely in there, in retrospect I should have removed him earlier since he stopped moving. He seemed ok when back in the DT by now died a few hours later

 

[Zacktosterone]

No way I have no idea what it could have been. Did you say you quarantined them first?