Converting to frozen food?

[Kevomac]

I got a bimac at a LFS last Friday (it's now Wednesday), and he's doing great! He's already fairly big (I know that means he won't live as long) at about 6-7" from the top of his mantle to the ends of his tentacles. At the LFS he was eating guppies voraciuosly. Since I brought him home he has eaten fiddler crabs (less than five minutes in the tank and he took right to them!), and live goldfish (not the best food, I know, but they're cheap, and readily available), and he ate some of a frozen smelt I offered him by hand. He has turned up his nose at offers of frozen shrimp from the grocery store, though. I have wondered if maybe the shrimp is old (been in the freezer for about two or three months). I read somewhere on here that someone is offering scallops from the grocery store. Any other suggestions on converting him to frozen food? I'd rather use frozen as live can be a pain and an expense (crawdads are $2 and fiddlers $3).