If they are just pets put a drop of selamectin on their neck. Selamectin is Revolution flea and tick medicine for dogs and cats. It will get rid of the mites fairly quickly and prevent them from coming back for a month, just like in dogs and cats. If you see mites on one rat then they are probably on them all. Give it a week after treatment and then completely clean everything they have come into contact with. If they are feeders I would not recommend feeding them to anything for at least a month after treatment.