about how big do derasas, squamosas, croceas and maximas get in tanks. lets assume adequate lighting and calcium levels. currently i have a derasa and crocea and plan to add a maxima and squamosa. i want to give them adequate growing room and do not want to put anything to close. currently my clams are about 4 inches in lenghth. also does anyone know were i can mail order a nice squomosa. most lfs only carry the other poular species. thanks for any help