First, lots more plants...at least 2x-3x as much as now...and give them time to adjust. Things may work out fine but they might not.
I have always fed the same things to all of the members of my Betta-based community tanks and fed at same time. I find frozen and live works better than pellets or flakes. When I feed I drop the food so it it widely dispersed all over the substrate so everyone has to graze.
If your dog thinks you are the greatest do not seek a second opinion