Is this possible?

[cuesport]

I had the same situation. None of my Koi were old enough to spawn, yet all of a sudden I had 18 (mostly black) tiny fish. One is light orange, a couple are turning orange and black, most are staying black. What are they?? I had a few goldfish in a separate pond but they weren't old enough too spawn either. When I built the larger pond, I only transfered the Koi. The babies showed up about 3 weeks later (in the larger pond). 13 of them survived the winter.

 

[koiguy1969]

most likely goldfish.. came into the larger pond via plant(s) or other item(s) transfered from one pond to the other or on a plant or something you bought..and golfish can spawn alot earlier than koi; goldies born in my pond last year were already going thru the motions.