I not quite sure what you mean by rehydrate but im going to guess that you mean frozen bloodworms or other aquatic animals and those would do fine, if you mean the freeze dried some say it causes bloat in aquatic amphibians cause of the air in the food but ive been using it for a year with my two dwarfes and they are fine, i should mention though that I have been feeding frozen the last month and they do seem to prefer frozen to freeze dried but ultimately they aren't picky. There are also pellets made specificaly for them but because mine are in with fish the frogs dont get the pellets before the fish do