What I have read is that Clams over 3" do not require feeding and can survive on just lighting. I have always feed my tank reef snow twice a week . I don't know if that is helping or not but I was feeding my tank before I got the clam . If you do purchase one try to find one that is at least 3" big you stand a better chance for sucess. You may pay a little more but it will be worth it. Smaller than 3" require feeding and have larger mortality rates.