How long do you let fish water sit out?

Fish water does not need to be left out to sit before adding it to an aquarium. In fact, it is ideal to use your water directly from the tap and immediately add it to the tank. Before filling your tank, it is vital to treat your tap water with a neutralizing solution or water conditioner to remove any chlorine or chloramines. Allowing tap water to sit out before use does not fully remove the chlorine or chloramines; only water conditioners specifically designed for aquariums can achieve this. Always follow the instructions provided with the water conditioner you are using.