it is my understanding that some of the frogs bred in some of the Asiatic countries are well trained in the art of ninjitsu. Stealthy little buggers and can kill a man with one flick of a toe pad....lol
seriously though. i would let the cultures of mushrooms grow for about a month or so before adding them into a tank established with frogs. you can probably grow them in a plastic container separately and then place whatever you are growing them on right into the enclosure