Can anyone solve this problem?

[Ventralis321]

I have a crocea with some bleaching marks on it. And the color is a bit separated if you look carefully. I've had it for a couple of months now and it was doing pretty good at first. i had another clam also a crocea that was doing this but healed over time. I am worried that this is spreading between my clams but i'm not sure exactly whats causing it. I have another Crocea with seems to be exhibiting some signs but not totally sure yet. Here's a pic.
<a href="http://photobucket.com/" target="_blank"><img src="http://i34.photobucket.com/albums/d117/C_Cobb/clam.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[Stoney Mahony]

What kind of lighting do you have? If only VHO's like it says in your tag you probably dont have enough light. At least get them off of the sand bed and up closer to the surface where the intensity will be better. Croceas can survive for a few months in low lighting conditions but will eventually expell there zooxenthella and die off.

 

[acrodave]

if the mantle from the others are blocking it will also bleach

 

[Ventralis321]

i was thinking it might be bacteria. I had a crocea live for a good two years before i was attacked my the dreaded pm. So i'm not so sure anymore that it's lack of light but i did just add some carbon out of the blue and took out some rocks giving more light to that area. Either way do you think it'll heal if giving some time with good water quality and left alone?

 

[Ventralis321]

well to give you an idea heres my tank
<a href="http://photobucket.com" target="_blank"><img src="http://i34.photobucket.com/albums/d117/C_Cobb/Reeftankpics21026.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[acrodave]

i would think so i have one get part of the mantle bit off and it did fine grew back.... but if a light issue should get back the zooxanthellae are the acros blocking out at light cant tell from the pick

 

[acrodave]

"pick"=pic. sorry

 

[Stoney Mahony]

Your tank is amazing, NICE! I think that it should recover if your other clams have been doing fine at that lighting level. Just keep a close eye on it and make sure you don't have anything around it that can sting the mantle and you should be fine. I have had clams expell zooxenthella and slightly fade and then come back to ultra in a week. I read that clams do this sometimes when there zoox concentration gets to be too much. All in all, your tank looks good and I imagine you have pretty stable parameters so I think it should come recover fine.