Black vs Extreme Black

I was told mine are ae/ae but honestly I don't know how you'd know that outside of a lab. There is never a single yellow hair at all, but there are sometimes gray hairs near the vent (hairs that would normally be yellow on a regular black mouse), but not on the ears. At first, I thought my mice had yellow hairs on the ears and on the nose, but I realized that it's the skin peeking through! In places where the fur is naturally thinner, you can see the skin a little bit and that's the only break in color.

I don't think it generally matters whether the mice in question are black or extreme black, because (and this is important) they're both bred the same way: never any outcrosses (no other varieties are suitable), highly inbred, small, thinner than other varieties...also, both can improve other varieties (like Siamese or blue), but those varieties don't really improve them. They're both also shown (in the NMC, AFRMA, and ECMA, at least) simply as "black." So whether you're working with non-agouti ("black" or a/a) or extreme non-agouti ("extreme black or ae/ae), basically everything is the same. The only time I can see that they would be different is in the case of tan. A good black can make a black tan. A good extreme black cannot (there are only two places for an A-locus allele to go and a tan mouse needs at least one to be at/* whereas an extreme black requires both to be ae/ae and leaves no room for tan).

Here are some pictures:


Regular good blacks--you can see the yellow ears and the pale tail.



An extreme black weanling versus a regular good black weanling. Notice the difference in ear color and pigmentation on the fingers as well as tail...even though the regular black has good pigment overall, you can still see non-black pigment in the toes, ears and tail. This is a fault.


An extreme black female's belly.


A good black's belly.


A regular pet store, i.e. "poor" black. This is the most common type of black mouse. You can see all kinds of unpigmented areas on this mouse.

You're not dumb! Everybody has questions!

The best way, if you're "starting from scratch," as it were, is like you said--breed only from the darkest blacks and those without pink toes or yellow ears. If they all have pink toes and yellow ears, select the ones with the least non-black pigment. That's how it was done originally in the 1800s. It definitely is possible to make improvements with 'starting from scratch,' but it takes a loooong time. It's taken around 120 years (and thousands of generations) to get mice as black as we have them now. If you draw a parallel to dogs, think of starting out with a wolf or a dingo and selectively breeding for dogs who resembled a pug. Is it possible? Absolutely. Will it take a long time? Yep.

Also, keep all other colors out of the breeding stock. If a chocolate, blue, or dove pops up (for example), do not breed from it. You want to get rid of all other recessives. I struggle with having Siamese in my blacks, and that's enough of a pain. I can't imagine having multiple recessives hiding around.

If you live anywhere in the Mid-western US, I probably can get you a couple good foundation blacks.