Clean 0. 5 gallon (2 liter) bowls daily, 1. 5 gal. (6 L) bowls three times a week, and bowls 3 gal. (12 L) and up twice a week. Ammonia levels rise quicker than you may know it. If your bowl has a filter, then you can cycle the bowl (which might be hard considering bowls are tiny and not humane), then you can clean the bowl once a week. Don’t ever clean the bowl once a month. If the bowl is big enough, then you can keep the betta fish in the bowl while you clean it and change 50% of the water. Doing that will help the betta fish to not be stressed. There are not a lot of filter options for small fish tanks, so they usually require more frequent upkeep than large fish tanks.

Clean 0. 5 gallon (2 liter) bowls daily, 1. 5 gal. (6 L) bowls three times a week, and bowls 3 gal. (12 L) and up twice a week. Ammonia levels rise quicker than you may know it. If your bowl has a filter, then you can cycle the bowl (which might be hard considering bowls are tiny and not humane), then you can clean the bowl once a week. Don’t ever clean the bowl once a month. If the bowl is big enough, then you can keep the betta fish in the bowl while you clean it and change 50% of the water. Doing that will help the betta fish to not be stressed. There are not a lot of filter options for small fish tanks, so they usually require more frequent upkeep than large fish tanks.

Do not use rainwater in an area with acid rain.

Skip this step if using distilled water or rainwater.

Leave at least 3 inches (7. 5 centimeters) of space above the water level in the new container, so the betta cannot jump out.

A sponge attached to a handle may be the easiest tool to use. You can use the same sponge to clean off rocks and other decorations too.

See the preparation section for more information on preparing aquarium water.

Keeping the old water also insures that you will still have useful bacteria in your fish bowl, which will break down otherwise harmful chemicals produced by your fish’s waste.

Never use any soap, cleaning products, or any substance besides water or vinegar to clean your fish bowl.