It is important to keep any tank clean, but it is even more important if you keep fish in a small bowl, since these containers usually have no filters and the small volume of water means that the contamination is more concentrated. It is especially important to clean the small bowls weekly because failure to do so can quickly result in disease and death to the fish.


Assemble these items:

  • Clean 2 cup container
  • Bucket
  • Water conditioning product
  • Small fish nets
  • Hand towel
  • Filter
  • Paper towels
  • Small brush


Unlike large tanks, where part of the water can be replaced at each cleaning, cleaning a small bowl usually means replacing the entire water supply. To avoid major shocks to your fish, it is essential that the water is treated to remove harmful substances and aged to equalize temperature and pH.

Regardless of your water source, it must be treated to eliminate chlorine, chloramine, heavy metals and other potentially harmful substances. Maintaining a consistent water temperature is also important to avoid stressing the fish with a sudden change in temperature.

Finally, tap water contains dissolved gases that dissipate after a short period of time, often altering the pH of the water, which is another stress factor for your fish. All these issues can be addressed by treating your water and aging overnight before adding it to your tank.

The process for aging water is simple:

  • Fill a clean bucket with tap water. You may want to buy a bucket to be used only for fish water, to ensure that it never contains any soap residue.
  • Add a water conditioner product. Choose a product that is advertised to instantly remove chlorine, neutralize chloramine and detoxify heavy metals.
  • Let the water rest until the next day before using it. If you have small children or a pet like a dog, place the bucket in a closet to ensure it is not disturbed.

After the new water has aged overnight, you can clean the tank.


When cleaning the tank, you will temporarily move your fish into a small container with water taken from the tank. Using this water will minimize shock to the fish.

  • Take some of the water from the tank and fill a small, clean container that has never been washed with soap.
  • Fish that don’t normally jump will behave differently under stress, so your fish will try to take a break. Reducing light will also help reduce stress on the fish. Place a hand towel over the container to reduce light and prevent the fish from jumping.


  • Quickly clean the tank as you want to minimize the time the fish spends in the temporary container.
  • Remove all decorations and place them on a clean surface or paper towels.
  • Place a clean filter in the sink and then pour the water out of the bowl through the filter, grabbing the gravel.
  • Put the bowl aside and wash the gravel with warm water, shaking it several times to ensure that all debris is washed.
  • While the bowl is still wet, use paper towels to rub the bowl’s internal surfaces. Do not use soap or other detergents.
  • If there are difficult stains in the bowl, use a small, clean brush to rub the stains. A new toothbrush works well for this. The same brush can be used to rub the decorations.
  • Wash the bowl and decorations several times with warm water.


All that remains is to reassemble the bowl, add the new aged water and invite your fish back to your clean home.

  • Place the clean gravel in the lower bowl, distributing evenly over it.
  • Arrange the decorations as desired.
  • Then fill the bowl with the aged water. Adjust the decorations if necessary.
  • Remove the fish from the temporary container and return it to the clean tank.
  • Use a paper towel to clean the water outside the bowl.


  • Feeding your fish sparingly will help keep the bowl cleaner between maintenance days. Overfeeding is the most common mistake made by fish owners.
  • Keep a couple of jars of water or cartons of clean milk full of treated water so that you always have aged water available for emergency water changes.
  • Use vinegar if your tank has lemon marks after cleaning. Put the bowl aside and put enough vinegar in the bowl to cover the stained area. Leave to rest for 15 to 30 minutes, then rub with a clean brush.
  • For algae stains in the aquarium or decorations, clean with a 10% bleach solution. Make the solution by combining 9 parts water with 1 part bleach. Soak the bowl and decorations in the bleach solution for 15 to 30 minutes, then rinse several times with cold water and let the bowl air dry.

Ned L. Bennett