Tridacna spp. First week in tank. 
Picture taken March 1999 with Minolta 7000 35mm camera with ASA400 film, no flash.
(Scanned Image)

I purchased this clam on April 28th, 1998. This picture shows the clam the first week I got it. You can see how the mantal lost its real nice blue color while under VHO lighting. (Picture above shows the clam after being under VHO lighting for a year).

You can also see how the life on the rock has changed. All the green macro algae has died back since this picture was taken.

Clam pictured here is under 2.0 inches.

Tridacna spp. One Year Later. 
Picture taken March 1999, Sony Mavica FD91 digital camera, no flash.

From the start it was a rather dull dark blue color-- which was exactly what I was looking for. At the time I only had VHO lighting over a 55g tank. I was told that clams with lots of dark brown/blue color did not need intense lighting (at least not as much as the gold, light blue, and deep green ones). I found this to be true - the clam did survive but not thrive. The clam was about 8 inches from the VHO lighting and grew well under them. However, what was left of any blue color quickly went away.

The clam was original purchased as a Tridacna derasa. However it does not show typical shell growth of a T. derasa. Some people on the Internet feel it is a T. crocea.

The clam pictured here was moved to my 180g tank. This picture shows the clam after 2 weeks in the tank under 250w Iwasaki Metal Halide lighting -- with no actinic lights. The clam is at the very bottom of the tank, about 30 inches from the bulb. I'll slowly move the clam up in the tank to see if will regain its color. Clam in this picture is about 3.5 to 4.0 inches in size.

Update: 05/03/1999 - Clam was found dead in its shell. Shell was wide open and did not react to anything. Appears it was not able to cope with the lighting change. On close inspection I could find no evidence of it being munched on.