First of all, though I don't post often I want to thank everyone here for introducing me to this hobby. I dreamed about it for years after first coming across this forum, and now I've been keeping and breeding fancy mice for two years. It's honestly been one of the greatest joys of my life when I didn't have much else to be joyful about!

So -- in a recent litter I got a color I can't recognize at all. A previous litter of 10 between the pair didn't produce the color, and the current litter of 7 had two.

I have the buck recorded as A* Cc ee Pp ss and the doe as A* Cc Ee Pp ss - across two litters they've produced 9 albino pups, 3 recessive yellow, 2 argente, 1 agouti, and then these two mystery pups.



Thank you again!!

This is a poor photo but the pair have a tan-reddish undercoat:



Thanks everyone

Marten Sable

Thank you so much, that's the only color I could find that was a match but I didn't think it was possible!

I have so many questions now and I'm not even sure where to start with asking them, this is so far beyond my comprehension

I've seen it speculated on this forum that marten sable can be produced from viable yellow or recessive yellow, is that proven fact? I've heard that lethal yellow is very rare in the US, and I had always assumed my buck to be recessive yellow. Is there any way to tell via test breeding whether he was Avy or ee (or both?)

Additionally, I've never produced tans before in my colony, although I plan on test breeding the two pups once they're old enough. Hiiret.fi says that marten sables can be produced without the tan gene, could this be the case for my two?

I'm also very confused about the chinchilla gene -- How is it possible to have an agouti mouse produce both albino and marten sable pups? Wouldn't an agouti-based mouse with both cch and c be a chinchilla?

Thank you for helping me learn!! I'm very excited to have this new color pop up in my colony, even if it is hurting my brain to try to understand right now

Another update, the lovely wonderful people of the Mouse Breeder's Alliance Discord server identified the mice as opals / blue recessive yellows! They were certainly very blue when younger



I hope this thread can be helpful to anyone who might come across it in the future looking for the answer to a similar riddle like I often do, I couldn't find a single photograph of any opals from a few basic Google searches (none that were identified as such, anyway) so hopefully this will make things just a bit more accessible!!