they float, and will escape if you have anywhere for them to grab on to near the top. You can smash them between your fingers in the water column if you are trying to get them to bottom feeders. That's what I do for my featherfin cat and polys in my African/Asian tank. The loaches, and bushfish take them from the surface.Do crickets float, or sink when they go into the tank?
Am thinking my Rays will prob enjoy them.