Hello,
That looks a little bad, but not awful. Did the end of the tail get pinched, it's a little hard to
tell in the picture.
Or, has he gone through a bad shed in which the skin has retained?
If it begins to get dark at the end or tip & the color travels upward & is becoming rigid then
that would be the tissue becoming necrotic.
For now, you can get some antibiotic ointment or raw, or manuka honey to put on the end
of the tail. .
Is he/she eating normally or does it seem to be bothering him?
Tracie