Hi I have a question about why my big fish keep dying> I had 5 fish that were on the bigger side and I added snails and they seemed to die off but since that incident it has been about a month or more and I bought a Maroon Pair and a type of tang it had the shape of a yellow tang but it wasn't a yellow tang. It is a 210 gallon aquarium that is getting turned into a reef tank slowly. The fish inside of the tank currently are 2 Maroon Clownfish, 2 anemones, 3 blue damsel fish, 1 hawk fish to be removed,1 engineer goby and 6 shrimp. I'm not sure if the arrow crab is still alive and I also have two small clown fish waiting to be taken out and probably 130 snails or more. Whenever I add a fish it seems to be fine for a week or two then looks stressed, sick and eventually dies and its happened to every fish that is on the bigger side except the maroon clown fish. I thought it was a parasite but nothing else but the tank looked sick and my other thought was the damsel fish are hiding in the rock and nipping at them when they are getting to close to the rock. Any ideas of what it could be or if I'm right about the damsel fish. Anything advice of what I should do so this stops helps.