Questions about Derasa Clam!

[Hoggn]

I have this clam in my 75 gal show tank now for about 3 weeks or so. I appears to be healthy, extends fully and the colors are bright. It is attached to a pc. of live rock after being placed there within 10 hours. It will close and open during feeding time. It will close if a shadow passes by. From time to time I noticed that it will appear to be gaping. Is this normal? When I feed the tank it will open up farther then normal and from time to time it will be open or closed. At night it always seems closed.

Is this normal? I feed him every other day or so. I use Kent's zooplex. The only parameter that is off is my Ca. It seems to be around 200. I'm trying to level that off a bit. Could my low Ca be causing a problem. I also have plenty of lights on the tank. I have 4 x 65 pc plus 2 x 28 pc plus 400 watts of MH. He is located about 8 inches from the top of the tank.

 

[Highlander]

The behaviour as you describe it seems pretty normal IME.
Your calcium level is horribly low though and will be a problem unless you get it up to acceptable levels, derasas grow quickly and are calciulm hogs.

 

[Hoggn]

Highlander thanks for the reply... I thought he was ok but with him gaping from time to time I just wanted to make sure he wasn't heading down hill...