clam fade

[axis]

I've had a derasa for about a year and I've recently noticed that it has lost much of its color. What's more, it doesn't seem as responsive to irritation as it once did. The color loss isn't localized to any particular part of the mantle.
It sits on a sand bed about 24" from a 400W 10K MH. Tank temperatures are consistently in high 70's. My nitrate tests are pretty old (they show none detectable) but there seems enough nitrate for the hair algae.
Is the fade normal?

 

[MiNdErAsR]

Axis,

[welcome]

Have you tried relocating the clam closer to the light? Do you provide phytoplankton to the tank? How large is the clam?

 

[axis]

Thank you,
It was 4" when I got it a year ago and is about 5-6" now. No, I haven't tried moving it closer to the light. Can derasa profit from more light than this?
Are clams this size still dependent upon exogenous phytoplankton? If so, that might explain it - a couple of months ago I decided to reduce the amount of DT's added in an attempt to reduce hair algae.

 

[jksmiley]

Clams require supplemental feeding until they're well into adulthood. In fact, since your light frequency is a little high numerically (10,000, instead of 5000-6500) you will probably need to feed the clam as long as you have it.

 

[axis]

Alright, I'll resume the DT's. Thanks.
Doesn't this species generally come from depths associated with the shorter wavelengths (10K vs 5-6k)?

 

[axis]

I thought I'd update you on my clam. Soon after I posted, I bought a refractometer. Where both my plastic hydrometers read the equivalent of 35 ppt, the refractometer read 40 ppt! I lowered the salinity over two weeks to the present 35ppt. At about 37 ppt I noticed a big difference in the clam. It has since colored up nearly completely (still a few faded areas) and has become more responsive Anybody have similar experiences with hypersalinity? I noticed that these symptoms are not given in Knop's book.

 

[kevinpo]

I don't know about hypersalinity and clams but I have owned my T. deresa for 3 years and have never fed it. Until this last Aug. I kept it under 175W 10,000K bulb with VHO's. I now have it under 400W 10,000K Ushio bulbs and VHO's. It was about 3"- 3.5" when I got it now it's 10"-11" long and has gotten a slight blue hue under the more intense lighting. IMHO supplemental feeding for clams over 3" is not required provided you give it ample light and have healthy water parameters.


Regards,
Kevin

 

[toptank]

Even with strong lighting if you are experiencing "hypersalinity" as you were the shell will not open completely and the mantles stay mostly retracted. Yes 40ppt is really high for a clam IMO. The same effect would also apply to "hyposalinity".

Clams have digestive glands,anal papilla and bowels so they must be feed but that also can be accomplished by waste product produced by fish which in turn is filtered through the gills. They can not survive on symbiotic alone.

IMHO, if your clam is losing color I also think it might be a lack of light. I know that you are using 400 MH but the normally lost of color means lack of intense light or a nitrogen deficiency

Barry