How to tell difference in Gender: Butterfly Koi?

How do you tell the difference between a male and female butterfly koi? My friend wants to know.|||Before they are at least 8"-10" long+ (around 2-3 years of age), it is VERY difficult to tell any difference just by looking at them. When they are bigger, it gets easier, because the females take on a more rounded, football-ish shape, and the males are much sleeker, built more like a torpedo.





Also, there is that raspiness or bumpy feeling on the insides of the males' gillplates, which females do not have. And, in males that are at least partially white/white on the head, the white will take on a slightly yellowish cast while females of that same color pattern will have more of a pure white. Many females (of any color) will also often have a "hump" on their neck/shoulder area, just behind the head - the fish with humps, in my experience, tend to grow faster and bigger than those with no humps.





By observing all of these characteristics and weighing them against one another, you can usually make an "educated guess" about the gender and be correct most of the time. However, the only sure-fire way to tell the difference between male and female koi (of any type - not just butterfly) is to observe them closely during spawning. The one being chased is the girl, and the chasers are the boys. The girl will often race around and nose up into the stems of plants, etc., then suddenly turn and flip her tale, seemingly almost out of the water. This is how she releases her eggs. The boys, who have been nudging and bumping her all along, will then immediately immitate her behavior, releasing sperm to fertilize the eggs the female released a split second before.





Hope this helps - good luck!|||It is difficult to tell the sex on younger Koi, it gets easier as they get older.


Females tend to have rounder bodies and rounder pectoral fins and their fins tend to be somewhat smaller.


Males are sleeker, with more pointed pectoral fins, and their fins tend to be larger.


Others claim the colors of males are more brilliant.


Older males have a sand paper like raspiness on the gill plates, and some claim you can also feel a roughness if you lick your tongue across the front of the pectoral fin.


The easiest way is when there is a particularly aggressive male chasing the females, with the proverbial nose up the butt, you look for other males chasing the same now identified females.





If your koi is old enough, generally looking down from the top you can tell the males from the females|||I just brought one home today. I have a feeling it's a she because she has a few admirers in our pond already...only way I know how to tell.