I've experimented with clams and mussels in the past and they are a lot more finicky than you think.i don't know about a pond ,but I wouldn't put them in a tank with other occupants,..without specific care they die and foul up a tank quite nicely.calms are filter feeders and need to be fed.i would take them and put them in their own tank and experiment a little with them..find out what they react to,how to feed them etc.