bleaching, too little or too much light?

roons

In Memoriam
i have 2 crocea that i had on sandbed , they had some spotty bleaching , so i moved them up to middle of tank, they looked better for a while, but now ones bleaching has gone from spotty to the outer edges of the mantle all around.....................im using 8 bulb t-5, 5 ab and 3 b+..............................?
 
From everything I've read, crocea's are very light demanding and need MH lighting. I have one about 12" from a 150W MH, and was told that even 150W may not support a crocea long term.
 
I think you should probably be good as far as T5 goes. How does your other clam look? Is it similarly colored? Same depth? It looks to be about a 3-4 inch clam, is that correct?
 
those are 2 different clams snpr....................im good? this bleaching spots isnt normal is it? i agree spoiled, i f i had to do it again i wouldnt have gotten them..............
 
If they have been on the sandbed for a year, then I think the problem is too little light. Crocea's should be mid to upper range in the tank, and like to be in the rocks, not on sand like some other clams.
 
there color looks nice and crisp. i don't think its a lighting problem. did you list you phosphate and nitrate #'s? have you changed, stopped or started any additives?

Critterkeeper has reported some local bleaching in wild Gigas that he thinks is from some type of disease but says it doesnt seem to effect the clams and doesnt seem to progress too much, i dont know if this could relate to Croceas but???? how long has this been going on and how fast is it progressing?
 
localized bleaching happens sometimes when you introduce a clam to a new light condition, especially one that is significantly different than its former condition. Probably not a whole lot to worry unless the bleaching area expands.
 
i never kept them on sand, on a rock on sand yes, then i moved them up about 6 months ago, they seemed to look better, but i did just change all my t-5s to new bulbs about a month ago, think this is the reason?
 
It could be the change. I went from 4 110 watt 10K bulbs
to 2 at 10K and 2 at 6500K and I am getting bleaching, but
this normally comes out of it. Had it happen when I changed
out 3 bulbs at once.
 
So let me see if this is right or if what I've read is outdated etc.
Clams with generalized bleaching all over the mantle is generally form lack of light or lack og nitrate and phosphates?
Clams with local bleaching is caused by shading of a certain area, unknown disease?
Please correct me if above is wrong and also add other causes...

Also, it was said above that the localized bleaching was seen in some wild populations and assumed as a type of disease. does it seem to be contagious? Wondering if many were found in the same areas with the bleaching or if they are just scattered amongst other perfectly healthy clams.
And as roons said is it posible for localized bleaching to ever fill back in?
Any info is appreciated, thanks
 
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