they are known for being difficult to keep...
scallops are usually in more turbid water where there is alot of proteins, plankton, etc in the water.
Most die of starvation because our home tanks dont have the constantly available food. If you just got him, say goodbye, not because he will necessarily die, but because he will hide behind the rocks. they 'clam' thier way into little crevices and such. I tried to place mine in the front of the tank several times, but he just 'clammed' himself to the back again.
They eat micro foods, like plankton, cyclops, zoplan, etc. Some have been known to eat small brine, although Ive never seen this. You shouldnt directly target feed them either, from what Ive read, target feeding can 'clog' thier filtering abilities and ultimately cause starvation. Turn off your overflow, put some filter feed in there, let the powerhead spread it around real well, then kill the powerhead for a little while to let the scallop (and corals too) suck up some of the food. Some people kill the skimmer too, but my skimmer is in my sump, so if the overflow is off, the skimmer is only skimming the water in the sump during that time.
Ive had mine for about 5 months, and he seems to be doing well.
The only problem with this type of feeding is that it causes the water to get crappy (hence the reason why most people only target feed) but large scale feeding is what they need.
If you feed well, leave him to move where he pleases, and keep your water in good condition (feeding this way = more filter media changes, and water changes) he will do fine.
They are alot more work than you would think, and most of them die.
Good Luck to you
Jessica / Shrimpi