About a year ago, when buying fish at Petsmart, the guy who caught our fish told us what sex they were. When we asked him how he knew, he said that a male will have long anal fins and that female will have shorter ones! Is that true? We were buying koi at the time also, maybe that's what he meant?? I don't know where he got that info! Anyone else ever heard this?

well, ive heard males have a thicker first spine of the anal fin but ive never heard that one before. if it is true it could help me a lot whe buying my bubble eyes and oranda tomorrow!

That couldnt be possible cause of the Fancys that are raised to have the longer fins. You can tell by the thickness of the anal fins but this takes a good eye on telling the thickness of them. Best way to try to tell is when its matting time (the white bumps on the face and the front fins also the butt).

Here's a pic I got from Koko that might help.