How do you tell comet goldfish male from female?

Question

How do you tell comet goldfish male from female?

Answer 1

have no idea

Answer 2

until theyre ready for breeding and spawning the male gets pimples on or by its gills and the female will have a swallon tummy.

Answer 3

Until they are preparing to spawn, you can't.  When breeding time, the male will develop white tubercules on his head, while females will not.