I have a surfit of goldfish in my pond. Despite never having kept fish before my initial stock of 12 has now grown to about 60+ and I need to reduce their number. Must be doing something right !
Does anyone know if goldfish can be put in a pond with koi carp please?
Don't see why not, but fish usually only reproduce to the capacity of the area they are in, if your pond was too small for them they'd be dying in their droves, so they're probably alright where they are. Also, when you move them you'll have no way of telling which are male and which are female, so you'll only end up with the same problem in a different place.
Goldfish and Koi carp mix ok in a pond along with tench, orfe, roach and rudd. I've got a mixed bunch of about 35 - 40, no problems. All you need to stay clear of is predators.
The only mistake I made once is to allow my nephew to add some sticklebanks. They multiplied and constantly attacked my other fish nipping bits of fin or tails, took me ages to get rid of them because they are small and damn fast!
Have you thought of selling your excess goldfish back to the petshop in exchange for food!!