Can goldfish interbreed?

I have 2 Sarasa Comets, a Shubunkin, a Koi, and a common Goldfish and I was wondering whether any of them can breed with the others. I really don't want any baby fish so just surrounded by case if I have to separate them I really want to know whether they can interbreed.
yes I saw a fantailed/comet hybrid one time
Yes goldfish can interbreed. Just like Chihuahuas and Dobermans, they are all variations of equal species. Koi are not goldfish however, and while they are closely related enough to interbreed, the hybrids will be dull colored.

photo of a koi goldfish hybrid
http://www.tnfish.org/PhotoGalleryFish_T...
Of course they can interbreed. But recounting males from females can be difficult.
They will all interbreed, some of which enjoy been bred for commercial fisheries, search out F1's and F2's drived from Carp and Goldfish, to produce fish with the power of Carp but slow growing traits of goldfish, although they've be around for only 6 or 7 years now they've not exceeded the 10lb mark while 7yr frail Common Carp would have packed on the weight and be 10-15lb.
Answers:    They will interbreed. They are all members of the carp family equal way that golden retrievers and poodles are members of the dog family. There really would be no problem near the comets, shubunkin and common goldfish breeding. I wouldn't worry about newborn fish as they are all egg layers and you can always remove the eggs when you see them. Also, nearby is a good chance that they would end up consumption most of the eggs.
That will definitely not happen. That's all i enjoy to say.

Theres no way that they will.. Imagine a koi breeding next to a goldfish.. actually its impossible.. if it was it would result contained by the death of the babies and the mother, or a MAJOR deformity.
How long can i later ?   Is this everyday behavior for my betta fish?   Is my guppy pregnant or sick?   Betta fish, mannish, is burying himself within the marbles at the bottom of cistern?