Im actually having this same problem, I can not get him to eat massivore sinking pellets, I have a 6'' in a 150 gallon that wont go up to the top of the tank so I end up cuttinp up small pieces of anchovies and let them sink down, which makes the water cloudy every time. And any sinking pellets are super expensive and my cichlids end up getting to all of them before they get down to the bottom