Derasa clam looking unhappy

[Oshanickreef]

i have had a 3” derasa for about 2 months now and it has been looking amazing until a day or two ago. Today i notice it mostly closed all night which is the opposite of normal. It was always very stretched out and would allow my lawnmower blenny to lay in it even. I have moved it into my frag tank to be safe from my coral beauty or blenny in case that is it but if that isn’t the issue i have no idea what it could be. It doesn’t have any pyramid snails or Vermatids. Also my tank doesn’t have bristle worms yet because it’s a pretty fresh system transferred from a 10 year old 90 gallon system.

Par = 300-550.
Sg = 1.026
Alk = 9.6
Cal = 470
Mag = 1320
Ph swing = 8.1-8.35
Temp = 77.5-78

Anyone have any ideas?

 

[Troylee]

Moving it around tank to tank won’t help.. mine stays pretty much closed when the lights are out and I believe it’s normal behavior..

 

[Uncle99]

Not the most demanding clam in terms of PAR.
What does it do through the lighting period and what does it do in the frag.
I have crocea, sqamosa, Dersa and maxi. Maxi and Crocea crave light and are mounted at the top, the Dersa and Sqammosa on the sand bed.
All are closed after lights out.

 

[exnisstech]

All are closed after lights out.

^this^ One derasa and two maximas here and they all close at night. Don't worry about bristle worms, I have hundreds crawling around and night and they bother nothing that is healthy.