Crocea not opening fully

[fishermike]

I have had a Crocea for 3 weeks. It was doing great, mantle extending fully and reacting to light. I have noticed for 3 days now that the mantle is not extending past the edges of the shell. It still reacts to light but I am worried about it. Any ideas of what may be wrong?

I have moved it to a different location in the tank but it still reacts the same. The water is good, no measurable amm, trites or trates. Calcium is 400, alk 9.8 and ph is 8.2.

 

[fishieness]

any new addtions to the tank? corals? fish?
im assuming you have proper lighting?

 

[fishermike]

No new additions. I did have a lobophylia start to deteriorate and it was near the clam, I have removed it though and i have not seen improvement. My lights are the Tek light 4x54w T5's. I have had the clam higher in the tank and lower and seen no difference.