All animals need a clean environment to live happily. Regular cleaning & disinfecting of the cage and runs is very, very important.
Fish need routine tank cleaning and partial water changes regularly too, depending on tank size and number of fish. Water quality is everything to a fish as is good air quality for us. In some areas, particularly around The Midlands, hard water is a potential problem and water might need to be treated before being used to replace lost litres.
Cages and tanks may need cleaning as much as once a week.