Rat question

Hiya I know there are a few rat people here so I have a wee quandry. I noticed a couple of days ago that one of my rats has a wee bald patch on his back at the base of his tail. It's not sore, he doesn't itch or anything, he's otherwise fine and dandy and there is nothing wrong with his brother (who he lives with) so just wondering really if anyone knows what it might be?

It's about the size of a 5p coin, probably not even that tbh.

Cheers! x

Dont know if rats get ring worm but get similar bald patches from that. May be worth checking.

They do indeed and this was my initial thought but odd it's just cropped up now as I have had them a canny while now and they don't go anywhere or have contact with anything else to catch it?

Could it be this?
http://www.ratbehavior.org/Glossary.htm#Barbering

Ooooh that's just took me to a very long list of ratty behaviours!

Ooops! Click on Barber and see if that might be your boy's problem

Oooh could well be as they are always grooming each other but it says they do it round the head and face mostly. I will see how he goes for a few days as I looked up ringworm and it looks far too small, the pics of rats with ringworm had much bigger bald patches. Will keep a close eye for now, cheers. x