For starters, I know absolutely nothing about koi. I rescued this little guy about a week ago from some kids who wanted to see how long it would take for him to freeze in a bucket of water outside. At the moment he is hanging out in my bare bottom 55 gal with my two tiny goldfish, until I can get him his own little bachelor pad. He is eating goldfish flakes and spinach. What is he? Anything special? Just an average little fish? I have no idea what I'm doing. Any info on him would be appreciated!
Added pics. For size reference, the little yellow goldfish next to him is about an inch long.