So feeding gold fish is not good for a couple of reasons. First they are not as nutrious as a pellet, basically they are worth about what is in their gut when you feed them. Second is the risk of disease and parasites, if you medicate them then your fish also ingest meds not intended or needed by them. Third and probably one of the top reasons to not feed gold fish is they contain a enzyme called thiamasine which inhibits the fishes ability to use b vitamines. That's an easy way of saying what actually happens when ingested. Not all "feeder fish" contain thiamasine but a few do. The other reasons go for other live feeders also.
Pellets are more nutrious over all. Is it you who wants to feed live or do you have fish that won't eat anything else?
Have you tried frozen fish or sea food like chopped tilapia filets or silversides for a whole fish? I breed snails for my puffer and I've lost a few colonies so I have had to start over. I don't want to feed snails from the lfs until they have been properly qt'd. Snails don't get ich and most other diseases but they can carry it around for a while. I don't know if mollies, platies, or swordtails contain thiamasine but may want to look into breeding something like them as
Magnus_Bane
suggested.