Can adding salt reduce the toxicity of nitrite to fish?
Yes, salt reduces the toxicity of nitrite to freshwater fish. Salt is a compound containing sodium and chloride (NaCl). Studies have shown that chloride reduces the toxicity of nitrite to fish, so salt can be added to provide the chloride ions that offer the fish some protection against the nitrite. Very importantly, the level of chloride required to do this need not be very high at all. Research suggests a dose of between 7:1 and 10:1 chloride to nitrite is all that is needed. So adding salt to protect against nitrite pollution should be safe even for salt-intolerant species, because only a tiny quantity is required. There is a Nitrite Toxicity Calculator on our website to calculate what you need. Dr Peter Burgess agrees that too many people incorrectly assume that a high level of salt is needed to tackle a nitrite crisis. Peter told us: “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 f
