Hi, they are pretty basic. I don't know the real Latin name. They were called "Freshwater Golden Clam" (no additional info available). These, to me seem different than the little Golden Clams with the concentric rings on the top of the shells. What I know is that they need very good flow in the tank. If they die they can foul your water pretty bad. If you have a decent number of snails and bottom feeders they likely will eat up the clam pretty fast, but you should look at them every day just to see how they are.
For a couple years I have wanted some clams and there is VERY little info about them. Heck I can't find their real name. I remember being a kid and we would go fishing and the lakes would have clams sometimes.
I waited until I had a pretty big tank just in case there was a death, with 72G, I am not as worried as I would have been with my 37G. I will post a few more pics sometime this week, my schedule is pretty packed.
The one clam really hasn't done anything, not even really move, but it seems he is still filtering by the small gap in the shell. The other one dove into the substrate with almost no visible shell vertically after 1 week. then it seems it scoots out above the top of the substrate a little more on a regular basis. It is above the top of the substrate about 1.5" now. They are around 4 inches maybe a smidge more.
Then the concern of some species will put off a cloud of tiny clam spawn and could be toxic. Get stuck in the fish gills?!?
Not too sure.