I have read that salt used in freshwater aquariums can reduce ammonia or nitrite toxicity and reduce stress, improve fish health.
Osmoregulation refers to the physiological mechanism fish use to control the amount of salt and water in their bodily fluids. The implication is freshwater fish are saltier than the water they live in so fish release bodily salts and take in water. Freshwater fish use special cells in their gills to take in the salts as chloride that is lost to the water.
When freshwater fish are stressed they suffer from osmoregulation dysfunction which is the loss of bodily salts to the water column. Adding salt in times of stress can help reduce the lose of bodily salts and correct the osmoregulation dysfunction. Salt also can reduce toxicity of pollutants and kill some pathogens (gill and skin flukes).
Ammonia has two forms in water, ammonium and free ammonia. Free ammonia is very toxic to fish and ammonium is much less toxic. There is an relationship between free ammonia and ammonium and this ratio is dependent on ph, temperature and the amount of salt in the water column, as salinity increases the total amount of free ammonia decreases.
Salt is a substance containing sodium and chloride. chloride should reduce the toxicity of nitrite by providing chloride ions that offer some protection to the fish. "For counteracting the effects of high nitrite, just 100 mg (0.1g) salt per litre is enough. This very low salt level is tolerated by virtually all freshwater fish, even catfishes."
Is this snake oil or should I try this science.
Frequently asked questions on using salt | Features | Practical Fishkeeping
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