the shell seems to be loose and half way open. Is it dying or what does this mean? Can anyone help or show me some pictures?
Clams have to do work to close the shell. Normally it is open during the day and closed at night to avoid getting eaten.
Try standing in front of your tank with the lights on then block the light from overtop of the clam it should try to close up a bit immediately. Also the mantle should unfold out overtop of the shell not stay inside if it does it may be stressed-- or sick?
I can't quite understand without seeing what you mean bye being loose?
I can show you a healthy clam I hope thats what you want to see?
Clams can get irritated by fish nipping at them ( feeding the fish more often may help if you are sure that is the case)
Clams can stay irritated for weeks my dersa was getting nipped by a fish and I got a eheim auto fish feeder and the clam is growing again and is open.
It took me 2+ weeks to spot the fish causing the irritation.
in my post at the bottom is a link to my tank as it was months ago and the 5th picture down is That recovering dersa I spoke of !
Hope this helps I Have a book on clams and went to a psas meeting about them once I am no expert But if you need more info p.m. me
Paul