I have kept a derasa clam in my tank with a flame angel for about 8 months no problem. The last few days I have noticed the clam's mantle pinched in a few places. So I spent some time watching the tank. Sure enough didn't the flame angel swim by and take a nip at the clam. It now seems unable to leave the clam alone. So my advice would be to not choose a flame angel. I will have to transfer the clam to my 25g salt tank
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