Derasa Clam's mantle curling?

[weap0n_X]

I've had this clam in my tank for about 3 months. Yesterday I noticed that the clams mantle was curling a little, it is still fully expanding though. Any reason why it would be doing this? Chance of survival? I have 2 250w MH over a 120g. I will try to get a picture hopefully today.

 

[ezcompany]

yes a picture would help. if its a little curling then i would not be concerned. if the mantle looks constantly ruffled, then it could be pm. anyways, pic first talk later