Hybrid?

[hebbes]

Several years ago, I added a few koi to my goldfish pond. I didn't realize how big the would become. I found them a good home, however. Some while later, I discovered a large (not as big as a koi), very shy, dark grey creature in the water. Could it be a hybrid?

 

[Mmathis]

Yes, it could be.

 

[HARO]

Yup. They CAN cross-breed, usually resulting in sterile offspring.
John