Why has my clam's mantle receeded?

[spankey]

I have a crocea that is about 5 inches from tip to tip. If that makes sense. When I got it, it opened up nicely. But lately after about 3 months the mantle looks smaller as if it can't open fully over the edges of the shell. I can snap pics later?

Just curious what causes this? My calcium is perfect and I have metal halide lighting. 20k dual 150 HQI's over a 46 gallon bowfront?

Thanks for the help or info.

Spankey

 

[mbbuna]

post some pics and also list the fish,crabs and shrimp you have

 

[mbbuna]

i just saw the post in the nipping fish thread. that could be it, what kind of blenny is it?

 

[spankey]

Bi color

 

[Big Boy69]

Yo homeboy (spankey), I thought you got rid of your clam???
Harpoon that Blennie out!!!
I now have 4 Croceas, 1 Max and 1 Squamy in my tank.