I made the mistake of taking in some orphaned fancy tails this spring. I tossed 4 of them in my pond which has shubunkin and koi. The offspring I ended up with are amazing. This new generation makes shubunkins look bland. I have everything from plain brown, to every color combination one could think of. I also found a few that went through the pump, and ended up in my bog. I've been told that the koi can breed with the goldfish, but I'm not sure if that has happened. At any rate, I have a really cool mix of fish. I am overcrowded, and am currently working on a 1500 gallon add on. I should be finished with the digging in the next few days. Missouri clay seems to be the majority of my dirt, and it is like digging concrete ( yes I'm digging it by hand ).