Nitrite Toxicity in Fish (English version)

Nitrite oxidising bacteria take longer time to grow than ammonia oxiding bacteria in fish culture system. When ammonia availablity is high and Ammonia oxising bacteria is more active than nitrite oxidising bacteria, nitrite toxicity is occured in fish culture system. Nitrite enters into blood through gills, also carries chloride into blood. After enering to the blood nitrte oxidised the haemoglobin from ferous state to ferric state, termed as methaemoglobin. Methamoglobin has low capability of carring oxygen, thus blood become brown, respiratory stress is occured, termed as brown blood disease. Fish liver damage is occured due to low oxygen, eventually fish die if water quality is not managed correctly.