City Water contains chlorine which is harmful to fish. In the past you could let this water sit out for a week and the chlorine would evaporate making the water safe. However, water treatment plants have added Chloramine which is more stable and does not evaporate. This means you must use a chlorine remover to make it safe for fish and other aquatic animals.
The small amount of chloramine added to water will not affect other pets (such as mammals and birds) and can be used regularly for watering and bathing animals 1. Plants are not harmed by water treated with chloramine 1.
So remember to use AquaSafe or other chlorine removers every time you add water into your pond.
