I recently bought a Yellow tang about a month ago. Out of no where my yellow tang stopped eating and was dead on the bottom of my tank. After a few moments I realized my clownfish was swimming alone, I than found my other clown on the bottom of the tank also passed. I'm not sure what could've done this. My foxface, damsels and 6 line are fine. My other clown is eating alright, moving around. The top of him looks like he was dunked in flower but it doesnt resemble Brooklynella (iv'e delt with that before). Any thoughts?? Params are great, Ammonia 0, nitrate < .25 Nitrite 0. Corals healthy, Anemone is healthy so i doubt its a chemistry issue.