Well, theyre cold blooded, so eating a frozen cube must cool them down a bit, but I dont know how bad it is. Ive been feeding one of my tanks frozen bloodworm and brine shrimp cubes for a couple years, and the fish in there take them down whole, and they are still fine. My dempsey often will hide by himself ater he eats a whole cube, and he doesnt do that after eating non-frozen food, so I always thought he must have cooled down a bit from eating it. I dont think theres any real adverse problems though, but I could be wrong.