We have a 8,000 gal koi pond. Last year we threw in some goldfish - I hate to say it - but as diversion to a mink that was killing the koi. We ended up catching 4 mink but not before they had killed off all but two of our beautiful koi. During the winter months we noticed about half a dozen gold fish getting quite large and enjoying the pond. They are about 6 inches now. We added 6 more 12 inch koi in the early spring and suddenly had hundreds of babies. I have put some in a tank and watched their growth. They are thriving and growing very fast. Now I am wondering. When do they get their color? And even more I am wondering, is there a chance the goldfish were old enough to breed? At what age can you tell a goldfish from a koi? Would the goldfish and koi have breed with each other with the size difference? What do you get in that situation? Any info is appreciated. Thanks, T.

Hi Tricia, and !
Such a big pond sounds like fish heaven!! And yes, koi and goldfish can interbreed with each other. To find out which of the babies are koi and which are goldfish, all you have to do is look at their faces, around the mouth area. Koi have barbels, one one each side of the mouth, while goldfish don't have them.
As for color, some fry are faster, some are slower when it comes to changing color. Anywhere from 1 month to even a year it can take.

The goldfish sound like there were big enough to breed. 6 inch is a nice size for an adult fish, they can breed already when they are smaller than that.....
Have pics of your pond and fish? Photobucket.com is a great, and free, photo hosting site.....

They can and will interbreed and if that happens they normally look like a fat bellied koi. Normally very tall instead of long if looking at them from the side.
Koi normally have two barbels on each side of their mouth but can have more which is much more common with long fins. At smaller sizes you might have too look really hard too see them but at 3" they should be easily noticeable.

I have the same situation and am beginning to think I have several different breeds of fry. I also have shubunkins in my pond. I don't see any barbs yet. What if they are crossbred (GF and Koi)- will some have them and some not?

As far as I know only koi will have barbels. If they are a hybrid they will not have barbels and will also be sterile.
With all different varieties in your pond you could easily have some koi, some goldies, and some hybrids. It all depends on what sperm made it too what egg.

All my koi frys started off white or yellowish in color.

All the Feeder or Comet fry started off black or light grey in color.

I hope this helps you to identifed them.

This was I tell them apart when the were frys.

hello this is t-hunter you wouldn,t want to get rid of some of those koi I have a new pond and need some fish let me noif you do tricia