I have a pond at home with a pet koi named spot. He's red with a large black spot.
That sounds cool and I'm sure provides a nice aesthetic. Are there any distinctive features of the koi fish?
They can be distinguished by their color, patterns, and scales.
That's cool, I think they are traditionally found or popularized in Japan. Do you only have one koi fish?
Correct, because they were first domesticated in East Asia and used for food. Yes, I only have one.