I don't feed my polys feeders they don't need them. Frozen Krill, Frozen Silversides, Frozen Bloodworms, and Massivore/Cichlid Gold that's all I feed my polys...Plus I avoid minnows and goldies for the reason above. (my RES is 5 years old and 4" because he was fed goldies and little WC for 3 out of the 5 years)
I feed all my fish feeders about once or twice a month. Goldfish contain thiaminase but are also pretty fatty. A lil fat never hurt any body..emphasis on "lil"...considering none of my staple foods have much fat in them.