[mps9506]

They are aquacultured outside. Trust me these aren't aquacultured the way coral frags are. They have raceways outside in Vietnam, the Phillipines and elsewhere where these guys are raised right alongside with giant clams headed for the food markets.
IMO these 1inch clams are very difficult to keep. And while I am a proponent of keeping a Trimma Goby in a 3-5 gallon tank I am against keeping clams in nano's.
They need light and food. Both of which are difficult to provide in nano tanks.

AFA as hardiness, I highly recomend looking for clams that are around 3" and larger.