Keep at it man. Predatory fish can go quite a while without food. They should at least come around to frozen soon. Good luck--obviously use common sense, if they haven't eaten after a week offer a little of their old food and try again. A healthy fish shouldn't refuse food to the point of starvation, but sometimes it can take a while for them to realize the "dead" stuff is food. You can try tricks to make it seem more lifelike, like tying a bit of frozen fish to a fishing line and letting it sway in the current of your filters.