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Photo by Hal
Fish in a saltwater aquarium always release ammonia right into the aquarium through their gills, urine, and solid waste. Uneaten food and other decaying organic matter also add ammonia to the water. The biological filter controls the ammonia. It is made up of nitrifying and denitrifying bacteria, which live in the gravel bed. If imbalances occur ammonia can become toxic, that’s why you have to test the water. Otherwise it will hurt their gill membranes, and prevent fish from carrying on normal respiration. High levels of ammonia quickly lead to fish death. It even trace amounts of stress fish, preventing their immune system and thereby increasing the chances of disease outbreaks and resulting in fish loss.