Sinking Frozen Shrimp for Stingray

Hello,

First time posting.

I just bought a 10" motoro stingray from another tank owner. I put his tank conditions in my profile, but the short of it is : 200 gallon with sump, sand substrate, ph 7, 79 degrees. Current tankmates till I sell them off. 4 angels, 10" fire eel, 20 large danios, and a few other small fish that will become food if i dont get them out soon enough.
He readily eats frozen food. I have a bag of frozen shrimp I had bought a few months ago that I would like to feed him. I got a few pieces to the bottom and he seemed to like them, but most just seem to float on the top. I was wondering if anyone had any ideas on how to get the shrimp to sink quickly to the bottom. Right now I soak them in a cup of tank water till they thaw, then drop them in. I have tried shaking them around in the tank. Pushing them towards the bottom with my hand. But it seems like they just keep floating back to the top where he cant get them. Does anyone have any ideas on a way to get the shrimp to sink? Also, does anyone have any ideas for a good name for him?

Ok. Thanks for the suggestions. I've found that as a frozen block, I can get most of it to sink after pushing at it from the top a bit, but small shrimp still seem to break off and float to the top where they go to waste because the other fish are to small to eat them.
I put them in a cup and squeezed them. It worked. But honestly its kind of gross. I know there are sacrifices that need to be made when you have a special needs pet to be fed. But, I was wondering if anybody might have more ideas on how to get the shrimp to sink to the bottom? Thanks for the ideas.