How to Maintain an Aquarium

swordtail aquarium fish
© Anthony Nelson

The amount of basic aquarium maintenance you have to do is directly related to how closely you follow the three rules of fishkeeping.

If the tank is overcrowded, if you consistently feed the fish too much food, and if you seldom do partial water changes, the filter system will be unable to keep the water quality where it should be. If you find yourself dealing with diseased and dying fish on a regular basis, you are almost certainly doing at least one of these three things wrong.


Basic aquarium maintenance is not time consuming if the tank is set up correctly and you go about it properly. You should get in the habit of looking at the fish closely every day or two, as well as checking the water temperature.

Aquarium Image Gallery

Once each week, clean the inside of the front glass (and the side glass if you want), change 10 or 15 percent of the water, and clean the outside of the glass. You could do this every ten days, but it is usually easier to remember if you perform maintenance on the same day each week.

If the tank is lightly stocked and you are careful about not overfeeding, this basic aquarium maintenance can be done every other week. Undercrowding also means that more extensive maintenance, particularly on the filter, doesn't have to be done as often either.

If you keep large fish that consume greater amounts of food and thus produce more waste products, you may have to change as much as 50 percent of the water each time.

Note that tank size makes a difference, too. Not only are larger tanks a more stable aquatic environment for the fish, but they also require less work than smaller aquariums.

When doing water changes, be sure to use what may be the most important accessory you can own: a hydro-vacuum. Essentially, the hydro-vacuum consists of a hose to siphon the water from the tank with a special attachment on the end that goes into the tank. The attachment is a long, clear tube that is much wider than the siphon hose.

Learn more about the proper way to maintain your aquarium with the use of a hydro-vacuum on the next page.

To learn more about freshwater aquariums, see:


Aquarium Maintenance: Hydro-Vacuums

aquarium maintenance, hydro-vacuum
Change the filter materials in your aquarium's power filter about every two to eight weeks to keep everything clean and running properly.
© Perfecto Manufacturing

To use a hydro-vacuum, push the attachment into the gravel and suck on the other end of the hose to get the water started. Make sure you hold the outer end of the hose lower than the rim of the tank. As soon as you see the water in the hose cross over the top of the tank, place the end of the hose in a bucket positioned below the water level.

You will see the gravel swirl around in the large end of the hydro-vacuum, releasing clouds of waste material that will be drawn out of the tank along with the siphoned water. By pulling the attachment out of the gravel and pushing it into the gravel nearby, you will be able to effectively clean the gravel bed without removing the gravel from the tank.


Feeling that this activity will disturb the nitrifying bacteria in the gravel, some hobbyists vacuum only half of the gravel bed with each water change, alternating from one side to the other each time. Cleaning the gravel really shouldn't have any ill effects on the bacteria, though, so this caution is probably not necessary.

Every two to eight weeks, depending on how the tank is managed and what sort of fish it houses, the filter materials in the power filter will need to be changed. If the mechanical filter material is reusable, place it in a bucket with some aquarium water and squeeze it a few times to clean it or simply rinse it with tap water.

If you use tap water, make sure it is the same temperature as the tank water. If you are using some type of bio-media in the power filter, follow the same procedure as for the mechanical filter material.

The granular activated carbon will have to be replaced. Once the carbon is saturated with molecules it can't absorb any more.

Some hobbyists test the carbon by tinting the water very lightly with a harmless food dye. If the dye is removed by the carbon, it does not need to be replaced. It is easier to simply use new carbon when cleaning or changing the mechanical filter material.

This is all the maintenance an aquarium should require. Do not tear the tank down, clean everything thoroughly, and then set it up again. This only destroys all of the beneficial bacteria in the aquarium, forcing you to break in the tank again. If an aquarium requires that kind of cleaning, there are severe overcrowding or maintenance problems that need to be dealt with.

To learn more about freshwater aquariums, see: