No need to worry, but you want to provide it appropriate foods. In nature, over half of their diet consists of algae. It's important to provide them with lots of algae to eat. In our tanks, they will usually eat frozen offerings as well, but may take a few days to begin eating, after being introduced.
If, after a couple days, it's still not eating, a store bought shellfish, frozen and then opened, sunk to the bottom of the tank will almost always encourage them to eat. Make sure that there's no other fish bullying it, keeping it from eating offered foods.