I've got two of the dwarf puffers. Wiped out 3/4 of my limpet snail population in one tiny 1 foot tank overnight. Used to have snails clambering all over the place, they wiped it clean. I thought it would eat hydra... it doesn't.... but they look very fat and happy with themselves anyway.

I wouldn't trust it with shrimp gary, even if they're larger. These puffers are quite bold.. even against creatures many times its size. Might snack on a leg or two off your shrimps if it had the chance. Not a fish for the community..