A great article from
Randy at Blue Ridge Fish Hatchery
We at Sunland Water Gardens have had a wonderful relationship with Blue Ridge for about 20 years. They provide some of the best domestically raised Koi and Goldfish in the United States. Since much of their stock comes directly from Japan they have a great quality Koi at a much better price than Japanese raised fish.
So often my customers will ask if a Koi is a male or female. Of course it is not reliably predicable at 3” or 4” but as the Koi grows you will start to notice some definite differences. Below is a great article that will educate you on the difference between a boy and a girl Koi… Enjoy..
IS IT A BOY OR A GIRL KOI?
by Randy LeFever
Blue Ridge Fish Hatchery
Customers tell me it’s one of the most frequently asked questions that they get. Is it a male or female? While it can be difficult to differentiate the two, it’s not impossible. Use these tips to figure out the sex of your or your customer’s koi.
The sex of a young Koi does not affect its body shape until it begins to reach sexual maturity, which is usually at around three years of age. Most females at this age will start to carry eggs and will tend to be more rounded and “blimp” shaped. Males are more streamlined and torpedo shaped. Males lack the swollen abdomen of females. Generally speaking, females will grow to a larger size than males. Take a look at the pictures below for an example of the two.
Generally by two years of age, male koi will start to feel rough to the touch, especially during the spring season as temperatures are rising. If you rub your fingers on the gill plates and along the side of the body, it feels like sandpaper. Females will be slick and smooth to the touch.
The male vent will be more con-caved in appearance where-as the female vent will be convex and slightly protruding with a slight pink appearance.
During the spring spawning season sexually mature males will chase the females, nudging them with their nose to encourage her to release her eggs. This will typically occur with two males chancing one female.
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Pond Talk: Sexing Koi – IS IT A BOY OR A GIRL KOI?