this always happened when i first got my p-bass. They take a while to eat, well in front of you. i would put little guppies in the tank during the day so i can watch but nothing would happen but when i wake up in the morning they would be gone. When they are that small they are still seen as food to other fish so it is instinct to hide and to be very very cautious at that size. Should be eating soon tho! best of luck!