I used a lot of goldfish when I filmed "Couple in the Water Lily Pond" in a swamp in the mountains of Nagano Prefecture. After filming was finished, I caught as many goldfish from the swamp as I could and kept them at home. The goldfish were a mix of species, including Ryukin and Ranchu, and I started with around ten. One day, one of them started targeting one of the smaller goldfish, and the others started pecking at it, and eventually that one died.
A few days later, it started targeting another goldfish. Eventually, that goldfish also died. Looking back, I wish I had separated them into different tanks.
In the end, after about a year, I was left with just two Ryukin goldfish, a pair of goldfish. They lived quite a long time after being left alone.
Because this pair were similar in size and shape, I often assumed the one swimming in front was the male and the one swimming a little behind was the female (this was a mistake on my part at the time; in fact the one in front was the female, with the male chasing from behind).
However, one day, one of them died, and it became impossible to tell which one was the survivor.
However, a few days later, the surviving goldfish laid transparent eggs. The eggs remained transparent forever.
The goldfish lived for about three years even after it was alone.
This work was taken with a film camera when the pair was still alive. I wasn't aiming for this photo, but when I developed the footage, I captured the two fish passing each other while interacting with each other.