How can orange and white goldfish produce black-backed offspring?

I have had an outdoor 65 gallon pond for 15 years with all orange, orange and white and all white goldfish. After all these years the fish figured out

I have had an outdoor 65 gallon pond for 15 years with all orange, orange and white and all white goldfish. After all these years the fish figured out how to make more goldfish late this summer. One is orange and white, four are all orange and two had black markings on their dorsal surfaces that have expanded to color all of their backs, dorsal fins and tails black. The bottoms are not black. How can this happen?

or:I have had an outdoor 65 gallon pond for 15 years with all orange, orange and white and all white goldfish. After all these years the fish figured out how to make more goldfish late this summer. One is orange and white, four are all orange and two had black markings on their dorsal surfaces that have expanded to color all of their backs, dorsal fins and tails black. The bottoms are not black. How can this happen?

or:Possibly. Depends, but most black isn't permanant.

or:Black-backed genes can come through from previous generations. Just like with humans- you can have two parents with brown eyes and brown hair that have a blond child with blue eyes because someone in the past looked like that. It has to do with recessive and dominant genes. If you want to learn more Google 'genetics' and how it works. :-)

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