I guess this would be helpful for would be breeders...^^
Compatible
1.Royal Blue x Steel Blue = 50% Royal Blues / 50% Steel Blues
2.Steel Blue x Steel Blue = 100% Steel Blue
3.Steel Blue x Turquoise/Green = 100% Royal Blues
4.Royal Blue x Royal Blue = 50% Royal Blues / 25% Steel Blues / 25% Turquoise/Greens
5.Turquoise/Green x Turquoise/Greens = 100% Turquoise/Greens
6.Turquoise/Green x Royal Blues = 50% Royal Blues / 50% Turquoise/Greens
7.Yellow x Ext. Red(no nr geno) = 100% Ext. Reds (yellow geno)
8.Yellow x Ext. Red(nr geno) = 50% Ext. Reds (yellow geno) / 50% Yellows
9.Opaque White x Opaque White = 100% Opaque Whites (some w/red or cream wash) *Female must be really clean to produce more clean fries.
10.Cambodian x Cambodian = 100% Cambodian
Uncompatible
11.Yellow x Turquoise/Green(no nr gene) =100% Turquoise/Greens w/red wash (F1) / 100% Turquoise/Greens w/yellow wash (F2)
12.Yellow x Opaque White = 100% Ivories (dirty white w/red wash)
13.Black Lace x Melano Black = Zero blacks unless both carry the gene for the other black.
14.Melano Black x Melano Black = Zero fries (pure female is absolutely infertile)
15.Blue x Red = 100% Multi-Colored (who wants one?)
16.Black x Red = 100% Multi-Colored (black geno)
17.Cambodian x Turquoise/Green = 100% Multi-Colored (cambodian geno)
18.Yellow x Yellow = 100% Pale Yellow (we want intense yellow)
19.Pet Store Bettas = 100% multi-colored
These are just basic stuff. Based on your experiences (esp. with metallics like gold and copper), feel free to add more about this topic.