I have a 29 gallon community tank, had 2 perc clowns, leopard wrasse and one small hippo tang for 2 years and was on cruise control. I know the hippo needs much more room he was the size of a silver dollar when we got him.(were leaving an apt and will upgrade) I got bored after 2 years and added a .5 inch clown goby and a mandarin from a reputable dealer. Within 3 days the goby and mandarin died, two days later our 2 year old beloved clowns were covered in a white parasite. I added copper, After the first clown died we bought another to keep the pair and even the replacement died. The hippo and wrasse are perfectly fine. Any light on this situation? I guess adding the goby and mandarin caused a parasite to enter the tank or stressed them to succumbing to an existing parasite. Thanks in advance.

