Fish continually release ammonia into the aquarium through their gills, urine and solid waste. Uneaten food and decaying organic matter also add ammonia to the water. Even small amounts of ammonia stress fish; large amounts of ammonia will kill fish. Ammonia is the #1 killer of freshwater fish. API AMMO-LOCK Freshwater and Saltwater Aquarium Ammonia Detoxifier works instantly to detoxify ammonia, chlorine, and chloramines in fresh and saltwater aquariums. It protects fish cells and promotes healthy gill function by eliminating fish stress caused by ammonia. API AMMO-LOCK Ammonia Detoxifier Freshwater and Saltwater Aquarium Treatment does not remove ammonia from water; it converts it to a non-toxic form. For best results, use as directed on the product label. If your aquarium tests positive for ammonia, do a partial water change, then neutralize the ammonia with API AMMO-LOCK Ammonia Detoxifier Aquarium Treatment.