I had always wanted Extreme Black and was overjoyed when I happened upon it when I bred a pet store mouse to a show quality buck, and bred an offspring back to him. A very dark, black male was born, who didn't have a single pheomelanin pigmented hair on his body - not even on his vent or underside. After a years worth of experimentation, I confirmed that what I had was the Extreme Black gene.
I tried breeding it into several lines, experimenting with its effects on pheomelanin further, but this came to a sudden halt when the line began falling sick over the drop of a feather. It was heartbreaking to have litters I was looking forward to, not do well and fall sick all the time before I could even breed them. So I decided to part ways with the line.