When fish are line bred for color, a lot of the typical determining traits like color and body shape are lost. Venting the fish or watching as they breed are really the only reliable ways.
Not really much of a way to tell with color or physical features bc the males and females look alike.
there are the usual signs head shape, tail length, and general size. But it take time for these traits to become obvious. It’s also easier when looking at both sexes together.
The best and most reliable way to sex ebjd is venting.
sometime you can tell with a side on view like my pic but most times you need to turn the fish upside down and get a good look.
male will have a hook forward and female will have a straighter tube