Going with male.
Pic of the fish right side up.
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Here's a top side pic in post #1 at this thread https://www.koiphen.com/forums/showt...ht=male+female
As I mentioned there ... While widely built in general, this koi has never seemed to develop a very eggy looking lower belly area.
When it was three years old and 22" in 2016, I put it in a spawning tub with two males. On the morning of the fourth day, the males went crazy over it, exhibiting vigorous spawning behavior and splashing for over half an hour. I thought surely this was a successful spawn. But then they stopped, and I could find no eggs at all.
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It may be both, some koi fish can change gender throughout their lives. This is called sequential hermaphroditism, which is when an animal starts life as one sex and later changes to the other.