Does anone know how to tell the difference between a boy fantail and a girl fantail. I have two but I can't tell if I have two boys, two girls or a boy and a girl.
typically the males are considerably prettier than the females, so if you have a dowdy little creature with small fins and not much colour it's almost certainly female, and likewise if you've got something very colourful and extravagant it'll be a boy.
Sorry fairkatrina, there are no colour or any other noticable external differences between the sexes ie both males and females have as equally long fins and bright colours.
The only way you can tell...and it needs an expert eye, is that females are plumper, especially in spring when spawning usually takes place. Males often develop spawning tubicles....small white spots over their head, gills and pectoral fins.