Best technique I find is to take some sinking mini hikari cichlid gold pellets and stuff them into small cut up raw shrimp and feed your datnoids this for a while. Eventually one day just throw in the pellets by themselves and the datnoids will eat one pellet and they'll figure things out. I have all my dats on pellets through this technique. Once you have them on this pellet, you can switch over to massivore or another pellet of your choice, its just that I find all my fish love hikari. Datnoids tend to like sinking compared to floating pellets.
Another technique is to have "teacher fish", basically you put in a fish that eats pellets, the datnoids see the fish eating the pellets and they'll learn.
Either that or you take the pellets and marinate them in blood/shrimp juice and feed them the pellets.
Go with the first technique, trust me it works