 How to change the water in a fish bowl You should change the water in your fish bowl at least once per week, if not more often. Regular cleaning of a fish bowl serves two purposes. First, it will eliminate any odors coming from the bowl. Secondly, it will help keep your fish healthy. If you notice the glass on your fish bowl is becoming hazy, then it is time to replace the dirty water with clean water. Relocating your fish Find a holding tank. Your fish will need to be placed in a temporary holding tank while you clean and refill their permanent home. So find a suitably sized bowl, container or bucket that will serve as a temporary holding tank. Use a bowl or container that has not been washed with soap, as the residue from many soaps can be harmful to fish. 2. Age the water. You will need to age the water you will use in your holding tank to equalize the temperature and pH balance. Let the water sit overnight after filling the temporary holding container to achieve the proper temperature and to allow the levels of chlorine in the water to neutralize. If you don't want to wait for water to age overnight, then it is wise to treat this water with a dechlorinator. These products neutralize the chlorine levels found in most city and municipal water sources. 4. Make sure the water in this temporary holding tank is the same temperature as the water in the permanent tank. You may also wish to cover this tank with a lid to prevent the fish from jumping out. Avoid direct light. Don't place the temporary holding tank in a window or under a bright light, as the heat from these sources can raise the water temperature, potentially harming your fish. Also, be sure to place your temporary holding tank in a place where children and other household pets can't bother the fish. Move your fish. Take your fishnet and scoop your fish out of the fish bowl and put them into the temporary holding tank of fresh water. Use a large bowl for this holding tank so that your fish have plenty of room to swim. When using a fishnet to transfer fish from one container to another, make sure the containers are close together. This will reduce the amount of time the fish is out of the water, thus reducing its stress levels. 7. You can use a small, clean bowl to transfer your fish. Make sure the bowl does not have soap or soap residue on it and select a rounded bowl with smooth edges. When using this method, simply dunk the small bowl into the fish tank and allow the fish to swim into it. Be patient and don't chase the fish around its bowl. This could stress the fish out. 8. Monitor your fish. While you undertake the cleaning process, make sure to keep a watchful eye on your fish and their temporary tank. Look for changes in their behavior, color and activity levels. The following signs should be an indicator that the water in the temporary tank is too warm. Hyperactivity. Changes in the fish's color. Yawning at the surface of the water although some fish, like labyrinth fish, breathe this way. If the water is too cold, your fish may exhibit the following signs. Inactivity. Sitting on the bottom. Changes in color.