Tap water should sit for at least an hour before adding any fish to the bowl. The water must be room temperature.
Tap water is not recommended for fish tanks. If it is going to be used, it should be treated first to remove any chlorine. Once it is treated, the water should have enough time to come to room temperature. Do not fill the tank completely up as the fish may jump out. It is also suggested that the new and old water be mixed for the fish to become accustomed to it. Fill a container with half new and half old water and allow the fish to sit in the mixture for 30 minutes before putting it in the tank.