Is this one male, or is it female? This koi is 29" and 7 1/2 years old. The vent photo was taken today. The second photo (from above) was taken a couple of years ago when the koi was 26". It was April 22, 2018, when females should be getting eggy. 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.