The frequency of cleaning a fish tank varies depending on several factors such as tank size, number and type of fish, and the presence of plants or filtration. Generally:

• Partial water changes of about 25-30% should be done every 1 to 2 weeks to maintain water quality. Weekly partial water changes are common for typical tanks.

• A full cleaning, including gravel vacuuming, cleaning decorations, and filter maintenance, is typically done once a month.

• Larger or heavily stocked tanks might need more frequent cleaning, while well-planted large tanks with established biological filtration might require less frequent water changes.

• Cleaning should be balanced so as not to disturb beneficial bacteria in the tank, which help maintain water quality.

• Cleaning tasks can be segmented: glass cleaning may be done more frequently (e.g., weekly) while filter media rinsing can be monthly or as needed.

In summary, the most common routine for a home fish tank is a partial water change once a week and a more thorough cleaning once a month, adjusted according to the specifics of the tank and fish species.