Many koi owners often wonder how to tell the sex or gender of koi fish. There are certains ways you can tell the difference between male and female koi. Koi sexing starts through observation. One of the best ways to tell the sex of koi fish is when they are feeding. You will have your best view of your koi at this time.

In order to tell the difference between male and female koi they first need to be old enough.

Here are the differences between male and female koi:

1. Male koi are slender and like a torpedo shape.

2. Female koi fish are usually fatter at the abdomen. When viewed from above you can see they are wider and rounder.

3. Male koi fish have breeding tubercles come breeding time. These are small white spots specifically on the gill plates. Don’t mistake these for ich.

4. The biggest way to tell the difference between male and female koi fish is come breeding time. When koi fish begin to spawn and lay eggs you will see the male chasing or courting the female. If you see a koi bumping the back end or side of a koi it’s a good chance that it’s a male.

Knowing the sex of koi fish is exciting as many pond owners can’t wait until they start to breed. Breeding koi fish is very neat to watch and new baby koi are always a bonus. Next time you look at your pond fish see if you can tell the difference between male and female koi.