Though safe for drinking by humans, monochloramine, like chlorine, is toxic to fish and other aquatic organisms at levels used for drinking water. Fish hobbyists or home aquarium owners must neutralize or remove monochloramine from water used in aquariums or ponds.
As with chlorine, fish (including fresh and salt water fish), amphibians, and reptiles are harmed by monochloramine as it passes through the gills, directly entering their bloodstream.
Products are available at fish and pet supply stores to remove monochloramine from aquarium water including: treatment products (drops or tablets) that remove both ammonia and chlorine, or iological filters (for ammonia) and chemical agents (for chlorine).
Aquarium owners should routinely test their water for ammonia and chlorine concentrations. Test kits are available at pet shops and aquarium products suppliers.