Great to hear you are trying to expand your frog's food choices and earthworms and feeder fish would be a great way to go. I would try to be patient with your frog. Maybe try feeding it in a small bare bottom cage with just the food item for a hour or so, see if it will take it then. It might just take some time before the frog figures out how to eat the food. I would also try a whole earthworm, appropriately sized for the frog of course, instead of pieces. It should be easier for it to grab it and whole prey items are always better. Hope that helps some. Btw if your profile picture is your pixi then i think you may have a female, a better picture would help though.