I've seen freshwater clams available online, (here, for example: http://www.****************/catalog_pages/misc_critters/clam_fresh_water.htm ) and was wondering what people think about them. I've done a little research online, and found that clam larvae are parasitic to fish, they live in the fishes gills. Anyone have any thoughts or experience here? At first glance they seemed ok, but I tend to think that any sort of parasite is a bad idea for a fish tank.