My waterpnd

Question
Hi Nick I have a big waterpond we have kio and fancy gold fish. My question is Do these 2 fish mate? I have 2 fish being forceful with 1 Can they be male or female? How can i tell?

Answer
No, it is impossible for them to mate.

Koi are carp. Goldfish are well...goldfish. They have the same colors but they are two VERY VERY different species.
They can not mate.

They are likely just fighting. No worries though, as koi rarely go that far.

-Nick