Sayra, you shouldn't need to scent the tilapia with anything else to make Snakems accept it. I'm not even sure what you might use that could mask the scent of fish. Normally we would use fish to scent pinkies etc. If she won't take the tilapia, trout is a safe bet.
On the question of worms.... regular earthworms are what you need to be using. Avoid those which you Americans call 'red wrigglers', they're toxic.