I have two Acans in my 29G BC. How do I know if they are still ok? I have them about 3/4 of the way up from the substrate. I feed them mysis from time to time. They're open and not closed up at all so I don't know if they're ok or not. I had my first death since I started my SW tank. my blue/purple ricordea died. that sucks big time since it was so pretty.