Mounting/Fur Pulling

[LittleWomann]

Hi guys, i'm a new Chinchilla owner and i really need some advice!

I have two chinchillas, both males (brothers) and i got them at the same time, they're roughly 4 months old and one is a standard (cheeko) and the other is a mosaic (Peppei).

I've had them for about two weeks now and for around a week the Mosaic keeps pulling on the Standards fur which is resulting in him having gaps in his fur and really thin parts around his back legs and tail.
I've tried blowing on his face lightly or tapping his nose or side of the cage to make him stop, which he does, but then he just continues again.

Also they both keep mounting each other, is this normal?

I'm not sure what to do, and it's keeping me up at night with worry, watching them, making sure they're not fighting.
They cuddle up to each other and both eat and drink fine.

Any advice? :help:

 

[Newt]

Sounds like they are coming into sexual maturity, and are trying to sort out who is dominant. I guess so long as they're not fighting it's okay, but if there is any future evidence of fighting, then you will have to separate them immediately, and possibly permanently.