I've lost 6 out of my 7 within the last 12 months. 3 maxima, 2 crocea and a squamosa. The survivor is a derasa. 3 of the clams that I lost I have had for around 5 years the others were 2-3 years. In my case I suspect either a pathogen or a species of pyram snails that prefers snails but will also go after clams. I took this picture of an trochus snail being attacked by them in my tank. The odd thing is that I could never find more than 1 or 2 of these snails going after the underside of the mantle of my clams and none were ever on the bottom opening. I'd see them here and there on the glass and other hard substrates in the tank but only occasionally near a clam mantle. As you can see in the picture they are swarming the trochus snail yet none are going after the derasa which would have been an easier target. Whenever I saw them doing this I'd siphon them out. I guess even a single one of these snails can take down a clam if they attack it often enough.
