Nice looking little squamosa, are the spots blue or green its hard to tell from the pic's. It looks very similar to my new squammie, but I can't get good pic's to save my soul. The problem is it will outgrow your 12 g tank in like 2 months JK they do grow fast though and you will probably have to put it in a larger tank in year or two. If you don't want to upgrade to a larger tank, don't get discouraged about the clams growth rate. When it does get larger you will be able to sell it for a very good price"especially if the spots are blue". Squamosa't are one of the easyer clams to care for and your lighting should be fine for it. Keep you cal alk and mag in check and you should be fine.