Why my 12 weeks pitbull puppy does not eat ?

i already tried diff foods i tried raw chicken boil a lil and beef, i even put chicken broth in the dog food. I tried almost all the puppy foods, well he eats but not that much always eat a lil and start running around. i dont have that much time to sitting around to wait for him finish the food and i dont want to leave the food there because ants.....plz help