Aiming4 Goldfish Care

I have four fancy goldfish which have not all been together during the mating season in April.
I am unsure of sex of fish , Can you tell their sex when not in mating season?
Is breeding goldfish very difficult for a beginner? Any tips on breeding fancy fantail goldfish would be very helpful .Have watched Expert [...]

I am breeding goldfish oranders and moors. But i somewhat seem to have difficulty in feeding after the four weeks of brine shrimp.