My goldfish Angel has had white little spots on his gills for a while, and I see him chasing Tera around a lot. They've had babies before but they all died. I don't have a separate tank, and it's too cold to do anything about babies until spring, when I want hem to mate. Lately, Sunny has been schasing Tera around with Angel. Sunny is too young to mate (not even a year old) and he doesn't even have white spots. Does ha do this for fun or what? I plan on trying to breed Angel and Tera this Spring/summer. I plan on getting a special tank for that later. What can I do to make them not so "frisky" until later? Or is there nothing I can do?

Sunny is probably practising and if you don't want them frisky then turn the water temp down slowly.

The thing with goldfish age is that if you haven't been there when they were born, or got your fish from the breeder itself, you never know how old the fish really is. You might have him for just a year, and he might have been small when you bought him, but it doesn't mean he isn't older than you think. A lot of those small fish are not really babies, they are sometimes stunted, which means they have been kept in way too small environments and never grew into their potential like they should have. Some just stay small gene wise, and we think that they must be young then.
A male doesn't have to have the breeding stars to be ready to breed - a lot of my male never show their stars at all. I have shubunkin fry from a pair of shubunkin since a few days, and besides the fact that the female has a much bigger belly, I could never tell if the other one was a male, since he didn't have the white spots on his gills at all.
If you don't want them to breed now, yes you can reduce the temperature in the tank, or just put a divider into the tank - male on one side, females on the other....

The thing about putting a divider in is that I have six goldfish and a corydora, and they all love the entire tank. Sunny now has white spots on his gills, but they don't seem to be frisky now. My heater broke, and the weather temp has been getting lower. I really don't know what else to say