The best treatment for mites (fur mites) in a rodent colony in my opinion is Dicholovos. It can be found in No-Pest strips often used as hangers for barns or homes. You can open up the plastic and place cut strips (it looks like a thick/yellow brick) around the cages.

There are more extreme options such as Ivermectrin added to water supply, but that is a bit more drastic.

If you need help finding the strips I have a bunch at work for a gardening store I run and can recommend local or internet sites.