I NEVER feed goldfish to any of my species. Tilapia is much better for nutritional value.
I have raised Tilapia for food. it is easy. They grow on the moderate side 1.2" per month.
Buy 100 Tilapia fingerlings. Gut stuff during quarantine in the cheap $5 16 gallon Walmart totes with a seeded V sponge filter or two.
By the end of a three week QT, you will have uber live feed for your fish.
The Nile Oreochromis grows the fastest and reaches sexual maturity the quickest of the three species sold in the markets as "Tilapia".
They will spawn from fingerlings within 8 months. More like 9 - 10 for the blue O's. I haven't tried the Moz. O. species.
Also if you want to buy the Tilapia from markets, whole fish are cheaper by weight. The junk that we throw out after "filleting" to Oreachromis is the best "stuff" to feed your fish. You could kill two birs with one stone feeding your family and fish with whole rather than pre-filleted.