they are incredibly easy to breed, once you have a female & male
I can't stop mine from breeding (well short of seperating them, lol), they can lay eggs a couple times a week when they're happy
. The best thing to use is spawning mops to catch the eggs, or live plants, the male will case the female for awhile until she's ready then usually they swim through the mop and your left with lots of little eggs
.
I usually remove the mop to another tank (they will turn round and start to eat the eges straight away so you have to be quick!!) you can either remove the eggs by hand from the mop (very time consuming and delicate) or better still leave the mops in place until they're all hatched and free swimming
.
Mine usually hatch within 24~36 hours, then cling to the side of the tank for another day then they start their hunt for food, lol. I usually feed them straight away with microworms and BBS, and lots of them!!!!!
Even at such a young age they are major poopers, lol, I've tried the rearing tanks with and with out filters from personal experience I prefer to do large water changes instead until they're older then use a preseeded filter from the adults tank, the water movement helps build up their muscles aswell and keeps them in tip top condition. You'll need a large tank for the young to grow in aswell.
They prettty much will eat anything but it's good to start them on a good quality growth food such as the TetraGold Growth Goldfish, which really helps with their colouration aswell.
What type of goldfish are you hoping to breed???
At the moment I have 2 tanks full of goldfish fry, they take quite a bit of work to keep in good condition but the effort is well worth it in the end