Croceas require the most intense light of the clams. Its also the smallest one of the
giant clams. Its usually the pricier of the clams as well. If my memory data base is not failing me tonight I do belive that it prefers to be placed in rocks. It will need halides for all intents and purposes to thrive.
Maximas are a close second on the light intensity issue. I have seen them in VHO or PC only tanks but they dont fair so well even when placed high in the rocks. Maximum size wise, its slightly bigger than the Croceas. They are usually placed on the sand as opposed to the rocks like Croceas.
These two types of clams are usually suitable size wise for the average aquarist tank as the other three usually get to be pretty big as in 12" to about 36" plus! You can still keep the other three and they will do well in your tank and they generally require less intensely lite tanks but still require some pretty decent light. They are colorful too just not quiet as brillantly as the Maximas and Croceas. But many can be quiet striking just the same. They all do an excellent job of removing nitrates from the water. Certian types of fish and Pyrimid snails can be a real problem for them though. Do some research before you purchase. Recommend that you purchase one that is 3 inches or bigger unless your really dedicated and can target feed them a lot. Clams are calcium hogs big time, so unless your doing some serious calcium supplementation you might want to hold short of the active on them especially if you have a
SPS tank. I have 4 Maximas ain my SPS tank and I drip kalkwasser like there is no tomorrow in a effort to keep up with the Ca demands.
I know this aint much but its about all I have to offer. Hope it helps a bit....
