I sort of had the same problem. Need to try them again with Tesla. I suppose you could keep offering it to them, that's really the only way to make a picky turtle eat his food.
I finally got Tesla to eat lettuce by getting a veggie clip and leaving it in the tank for a day or two (it's broke now though :<). I also got him to eat some sweet potato, tomato, and carrot by warming it up slightly and making it smell. You could always try something like that if the shots keep failing. Or try soaking them in tuna water to make them smelly. Turtles love stinky food.
