Hello! I just got a clown fish a few days ago. He has yet to eat any food I've given him. What should I do?

He is a tomato clown fish. He's been in this new aquarium for almost three full days. The recommended food I'm trying to feed him is krill (the frozen food alternative.) I've heard that fish can be shy and not eat, but how long should that go on? Also, he seems to spend a lot of time at the bottom of the tank in the corner. The PH, salinity, nitrate/nitrite levels are all nearly perfect and the water temperature, along with my heater, is about 80 degrees. Am I doing something wrong? Is this normal behavior for a clown fish? Please help! Thanks!