It might have been asked before on here but honestly i did not read every comment , will clams move if they are not happy where they are placed ? and does the extension of their mantles give any indication of needing more or less of light , flow , etc .....
i have a 6" maxima that ive had for about 2 weeks , originally had it in the sand but read a lot that these types prefer and are found mostly on rock formations so i moved it higher and onto a rock ledge , its been there and hasnt moved , it also has not released its " strings " to attach yet ? it does react quite well to fish movement and light however the mantle does not not extend to much further out than the outside of the shell , just want to make sure im doing everything i can ?
established tank for 5 years
I have never had a maxima 6" and larger put down attachments. When they are larger they don't do it often so no worries. Clams will move a bit if not happy, but some move even if they are happy (strange critters) and some will not move even if unhappy. Helpful right? In general though if not moving then it's a good sign.
I have not found mantle extension a useful indicator unless you have had it a while and know what is "normal" for the individual. Of course for flow it's easy to tell you don't want the mantle curled over.
Wild.maximas don't open up much, and it's possible a fish is nipping keeping it closed. But too much fussing over it isn't good. If one gets concerned can put a clear container over the clam and see if extension improves then you know something is picking at it.
I do notice when clams get enough light they tend to close up a bit, but to notice you have to know what is normal for the clam.