So I have three glow fish, not sure what genders yet..
But I figure they'll probably breed.
On is red, one is yellow & the other is orange.
If the red & the yellow one breed, will the offspring be orange ?
How does that work?

Pretty sure they are one or the other. If you do breed them you cant sell them, they are patented.

After reading about it more Dan M. Said this in a previous answer, much better explination.

"The genetics of the color does not work quite as you'd expect. Reds may produce reds, but also other colors. Yellows and greens can reproduce themselves but not "throw" any reds. with each generation, a percentage of the fry revert to the gold version of the zebra danio, the one used for grafting on this gene from a fluorescing marine animal. It may be the new gene is not tightly attached and can fall off, but what actually causes this reversion, I'm not sure. Perhaps after a few generations, more and more revert to original, but I don't know of anyone taking it far enough to say." pets question and answers,www.5d2d.com

Here is the question and entire answer

the colors wont mix together, who ever has the .dominant' color gene when breeding will be the outcome of the color.
for example if the red and the yellow fish mate, the red may have a 'dominant' gene over the yellow one, meaning the next fish will be red