I think in mature goldfish the males will have weird spot/hump thingys near their gills and pectoral fins
beckers4oranges
#5
yea I think that's right...how many goldfish do you have?
Butterfly
#6
This is as close as I can get to sexing Goldfish.
Carol
Jason
#7
Have a look at that from what Ive read that is the most accurate way of distinguishing. I think the males have to be about 1yr old.
Skadunkadunk
#8
During breeding season, which is spring, ifyoulook closely, youcan see white spots develop on a male golfish's gill plates.
Jesse12
#9
its hard to tell since goldfish can change sex
jinx_beta
#10
There is no reliable way to tell the gender of young goldfish.
However, during the fishes breeding season, if you look to see if the fish has white pimple-like bumps on their heads and gill covers, then that fish is most probably a male. The bumps are called 'breeding tubercles' and they develop just before the breeding season. But after the season ends, these bumps gradually fade away (or are locked up until next season).
Another way to tell the sex of your goldfish is to have a look at the colour of their scales during breeding season. The males colour intesifies, to impress the female (dur!