Not neccessarilly. There are some very well bred fancies that are slow to colour up.
Provided the fish has been reared properly, a goldfish is usually mature enough to breed at about 2 years old. You will only know if it is mature enough during breeding season (spring time) when the females get chubby tummies and the males develop white spots on their gill plates when they come into breeding condition.
They are Goldfish and so they mature and breed as goldfish. They can be sexually mature at 1 year if they have been well housed and well looked after.
Goldfish can not get pregnant. They are egg layers. The female sprays thousands of eggs into the water in the breeding season (spring) and the eggs are fertilised by the males after they have been sprayed out. The eggs then take a few days to develop into baby fish (fry).
Goldfish can only be sexed when they are mature enough to breed and it is also breeding season. At this time the males have white spots on their gill plates and pectoral fins. The females just look a bit chubbier than the males.
Well, they have to be mature also, which is about a few years of age.
This info is from the internet: if you want to get some baby goldfish, the most fascinating way of obtaining them is of course to breed goldfish in your own aquarium or pond. A goldfish becomes sexually mature when it is around one year old, but will not reach their prime until two years later. It can be hard to distinguish a male goldfish from a female goldfish, but when they become mature the female will usually become a little plumper than the male. The male goldfish will develop small bumps on his head, and when the spawning period begins those bumps will be easier to notice since they will become white. Someone says they eat worms, but they don't so don't try it.
You will have to wait until the fish is mature and then you will have to observe it during breeding season (Spring time) If it develops white spots on its gills and sometimes pectoral fins also, it is a male. If it gets a chubby tummy it is a female.
It is common for young goldfish to have dark makings that eventually disappear as the fish grow/mature.
There is no size requirement for a goldfish to be mature enough to breed. The reason I say this is because so very many goldfish are so badly housed and treated that they may become fully mature but only a couple of inches long. Goldfish can usually breed within a year from hatching if they are well looked after.
Determining the gender of goldfish is a lot harder than people may suspect. During breeding season, the males will get what we call breeding stars on the cover of their gill plates; they look like tiny white bumps.You might also be able to tell by their vents under their tail, but it takes a lot of practice and knowledge to easily tell them apart when it's not breeding season.In addition, even if it is breeding season, and you have all males, or all females in your tank, it remains difficult to tell the difference as the males need a female in the tank, and vice-versa for the females so that they will show typical breeding behaviour.
The easiest way to tell the difference is that the males may get what are called breeding stars on their gill plates during breeding season. The breeding stars look like small white bumps.This is not always the case though, and sometimes the only way you know is by seeing the female drop eggs, or the male fertilizing the eggs.
A male Yorkie should be at least a year old to start breeding, and it's better to wait until he is closer to two. This gives him time to mature and allows you to make sure he does not develop any genetic faults that he might pass on to his puppies.