I feed mine frozen brine shrimp from packages and sinking pellets. Its a healthy diet for my senegalus polys and the love it! Once in a while ( don't do it anymore), i fed them feeder guppies as a treat. i stopped doing that because it can introduce disease and increase the aggresion of them. Good luck with ur polys.
I feed mine sinking carnivore pellet daily and frozen food 2x a week. Once they get larger they will be getting tilapia fillet and market shrimp. My Senegal is always excited to eat and comes out once pellets drop in, but my Delhezi is the complete opposite.
Mines only about 4" right now and i feed him half a cube of blood worms in the morning and the other half when the sun goes down, planning on mixing it up with some pellets soon but he loves it, get that big belly look!