I had the same problem with my turtle he went off his food and wouldn't eat anything .. not even ox heart
When I was in New World last week I notice in the frozen fish part these packets of "Kingfisher" chunky seafood marinara it has - shrimps, mussels, squid tentacles, clams - and my turtles LOVES it .. now when I am holding the food at his tank he comes straight over and snaps it up
Give it a go!!