I've seen these in every Asian grocery store I've been in. They are labeled as "Silverfish" and sell for around $2.99 / lb. They are about the size and shape of a bean sprout (about 1/2" to 1") and look like really big mysis but when you look close they do have discernible fins and skelelon. I tossed a couple in the tank and my fish and BTAs went nuts for them, but then again I guess they go nuts for any food I throw in. These seem pretty substantial though and cheap, and I was wondering if anyone knows anything about them. They're already a nice size, so if they're relatvely nutritious, they'd be much easier than getting a "seafood mix" that you gotta chop up first.