Where do the nitrogenous wastes come from?
Ammonia is the end product of protein metabolism. It is toxic, so all animals have methods for getting rid of ammonia as quickly as possible. Fish mostly get rid of ammonia through their gills. Bony fish excrete the ammonia directly, whereas cartilaginous fish (such as stingrays) produce urea instead. Either way, the ammonia gradually accumulates in the aquarium until it reaches toxic levels, at which point the fish will die. Two factors affect the toxicity of ammonia: pH and temperature. Ammonia becomes more toxic as pH and temperature rises. For this reason, fish in marine aquaria or tanks containing African Rift Valley lake conditions are particularly sensitive to high ammonia concentrations. One misunderstanding newcomers to the hobby have is between the visible wastes on the bottom of the tank and the invisible wastes in the water. For the most part, the solid wastes are faeces and decaying plant material, neither of which contain much ammonia. Though unsightly, these are not a th
