Do Croceas Change Colors???

[NaH2Ofreak]

I have about a 4 inch crocea clam that has been in my tank for about a year. He was solid blue but is now developing areas of brown on his mantle (both sides). Is this just a normal color change or is it bad. Could it be caused by not enough light available?

Thanks
Dennis

 

[mbbuna]

what lighting do you have and how old? how far is the clam from the light

 

[NaH2Ofreak]

The tank is a 125gal 4x2x2. The lighting is 2, 250DE,pheonix bulbs and 4, 4', VHO actinics. The problem was that the one clam that is changing color was shaded by a growing monti cap. I've since moved the clam out into the light but it continues with it's "browning" areas. The lighting is all about 4 months old. All bulbs have been replaced every 6 months for the past few years.

I was wondering if in your experience mbbuna, if tridacna mantles have a tendency to "brown out"? Kinda like how some SPS do.

Dennis

 

[mbbuna]

clams will brown out if there not getting enough light or the wrong spectrum of light

 

[NaH2Ofreak]

Well, I suspect that is what's going on.

Thankyou
Dennis

 

[Killdmycobra]

<a href=showthread.php?s=&postid=11057566#post11057566 target=_blank>Originally posted</a> by mbbuna
clams will brown out if there not getting enough light or the wrong spectrum of light

What spectrum of light is needed for a Crocea? I was just wondering what you mean by this statement.

Jeff

 

[ROB2005]

From my experience they will thrive best under 10,000K spectrum of metal halide (pure white with a faint tinge of blue).

 

[NaH2Ofreak]

That is a good point. Do you mean if the spectrum is too low K for the wattage? I think thats what you mean. ie; a 15K 250W bulb would be better than a 20K bulb.


Dennis

 

[mbbuna]

in the wild clams come from shallow water where they receive full spectrum light in the 5000k to 10000k range. they have evolved for thousands of years to this spectrum(s) of light. clams house multiple types of zoox that use different wavelengths of light for photosynthesis, some use red light, some green, some blue. when you place them under light that is focused on one wavelength like high K bulbs are, what ever type of zoox that uses that wavelength best will become dominant. however there is less total usable light for photosynthesis so the population of zoox has to be larger to meet the clams needs(zoox are brown) the clam will also reduce the amount of protective pigments it produces to let more light through to the zoox.