Breeding gold fish is not a easy task especially for begginers.If this is your first time you can opt for molly fish which is extremely easy to breed even in small tanks.However if you determined to breed goldfish then you need lots of work to do.You will need approx 20 gallon tank with live plants in it and 2 females goldfish with 3 males ensure the fishes are in healthy state.I hope you have aready differentiate between their sexes.However it is easy to differentiate them during spawning time.You can check blog archive to see deiffernces.Feed them live food like insect larvae,worms and brine shrimps.
How to spot spawning time:
Females become heavier and thicker due to eggs.
Males develop white spot on gills when they got ready.
Spawning usually occurs in the morning.
Color of fishes become more brighter.
Males chase females at random.
Then particular males chases one particular female more then before.
The male gets aggresive and push against females till she ejects egg.
When the eggs are out male deposits milt on them.
Then the eggs fall in water and on plants till they hatch.
The spawning may begin after some days of rest.
Note:The goldfish are egg eaters so remove them after spawning.
Set temperature to 21ºC .
Put few drops of methylene blue to prevent them from fungus.They are not neede to be fed till 24 hrs because they have egg yolk sac.After hacthing they will sink to bottom of the tank try not to disturb them .The process of sinking is normal.When sac is absorbed feed them baby gold fish food or hard boiled egg yolk.After it shiphone the uneaten food
but not babies.