I had velvet outbreak and lost most of my fish. Fish went into 35 days of Copper (2.25-2.50) then another 30 days of observation. The remaining fish (yellow coris, Red Velvet, Lawnmower and Coral Beauty) never showed any signs or symptoms. The yellow coris, Red velvet and Lawnmower were added back to DT two days ago. The Red velvet does pick on the YC every once in a while. The YC has started the odd behavior of swimming at the top actually breaking the water surface. everyone is eating fine and parameters are are normal. No inverts were added during DT 65 day fallow period. Any thoughts on this?