My understanding is frogspawn will get 99% of its nutrients from the light. The rest it will get from the water column. I suppose they could be given a morsel every once in a while. I have had mine for about 2 months now and I dont feed it anything. Each day it comes out and looks healthy.
Frogspawns don't need to be spot fed.
Since I have to spot feed my Gonio,I give some to my Frogspawn too usually mysis.If you want rapid growth then by all means spot feed a couple a times a week.I started with 3 branches and now there's maybe 12-15(2+yrs).