How Do You Tell The Difference Between Male And Female Goldfish?

The male is usually on top

lol

Typically by color.  The more colorful are typically male.

Mine  is white dumb ob-um (banana)

You can tell by their colour one is dark one is light

It is not easy to say that male & female by its color.

The female goldfish has a longer tail than the male.

How do you tell a female goldfish from a male goldfish, Is it the color, Is it the body and shape

This is not easy as these fish do not have distinctively gendered genitals in the way that mammals do. Male gold fish, shubunkin and carp are generally more slender in shape than females. Females tend to be chubbier and almost pear shaped. However, as fish do not eat in the colder months and survive off their fat reserves their shape will be misleading outside the breeding season. In the warmer, breeding months the males develop distinctive spotting around the gills and on their heads. These little bumps are white and quite noticeable during the breeding season. Watching their behaviour at this time will also offer clues to gender. The male fish try to stimulate breeding by chasing the females around the pond or aquarium. They deliberately bump into the females to stimulate spawning. However, if you wait until you see these signs it will be a little late to start a selective breeding programme. Once the female has spawned the male will quickly deposit his milt over her eggs. Fertilisation only takes 20 minutes and so, by then, it will be far too late for the fish keeper to intervene.