I have 3 clams currently, 2 maximas and 1 crocea. I have a Foxface, clown, sixline, scooter, bluejaw trigger, scopas tang all in there with them. The most they ever do is clean the outsides of the shells on occasion when necessary. In fact, when I got my second maxima it had quite a case of bubble algae on the shell and the Foxface and Scopas took care of it in 24 hrs. Didn't even knock the guy over! I also have a couple peppermints and a fire shrimp in there and the most I have ever seen them do is clean around the mantle, never really bothering them even to the point of closing up. Did have a bi-color blenny I had to part with as he was bothering the crocea. I would not recommend them in a tank together. My royal gramma is occasionally a poker at my maxima also, but not a real pest, he will just close up for a minute or two and then open right back up again. Hope this is some good info for someone out there!