Do fish really need water conditioner?
Maybe. If your drinking water comes from a municipal water supply or other public water system, then most likely it is disinfected with chemicals like chlorine or chloramine to eliminate bacteria, viruses, and other microorganisms that can cause diseases. These chemicals are toxic to aquatic animals and beneficial bacteria and therefore must be removed from the water using a dechlorinator. If you forget to add water conditioner to the tap water, your fish’s gills may become burned, causing them to start gasping or breathing heavily.
If your drinking water comes from a well or other water source that is untreated with chemicals, your aquariums may not need water conditioner. We suggest getting your well water tested to see if it contains any heavy metals because some dechlorinators can help remove them.
For more information, read the full article on dechlorinators.