Changes

Nitrite is transported across the gills where it enters the bloodstream and oxidises '''haemaglobin to methaemaglobin'''. This leads to tissue hypoxia.

Nitrite is transported across the gills where it enters the bloodstream and oxidises '''haemaglobin to methaemaglobin'''. This leads to tissue hypoxia.

Nitrate toxicity is particularly a problem in '''newly-established recirculating systems''', in which insufficient numbers of bacteria are present in the biological filter. This can also be a problem when the biological filters have been damaged by the interruption of water supply, '''excessive cleaning''' or '''antibacterial administration'''.

Nitrite toxicity is particularly a problem in '''newly-established recirculating systems''', in which insufficient numbers of bacteria are present in the biological filter. This can also be a problem when the biological filters have been damaged by the interruption of water supply, '''excessive cleaning''' or '''antibacterial administration'''.

Species susceptibility to nitrate is '''variable''' and is linked to '''chloride uptake''' by the gills. Nitrite competes for chloride absorption, therefore fish with a high chloride uptake such as the rainbow trout, the perch, the pike and the catfish are more susceptible to nitrite. In contrast, the largemouth and smallmouth bass, bluegill and green sunfish are resistant to high concentrations of nitrite.

Species susceptibility to nitrite is '''variable''' and is linked to '''chloride uptake''' by the gills. Nitrite competes for chloride absorption, therefore fish with a high chloride uptake such as the rainbow trout, the perch, the pike and the catfish are more susceptible to nitrite. In contrast, the largemouth and smallmouth bass, bluegill and green sunfish are resistant to high concentrations of nitrite.

==Clinical Signs==

==Clinical Signs==

==Treatment and Prevention==

==Treatment and Prevention==

Nitrite is much less toxic when '''chloride''' is present, possibly because chloride inhibits nitrate absorption across the gills.  

Nitrite is much less toxic when '''chloride''' is present, possibly because chloride inhibits nitrite absorption across the gills.  

'''Sodium chloride''' is the most available and cheapest source of chloride.  

'''Sodium chloride''' is the most available and cheapest source of chloride.  

Haemaglobin levels should return to normal within 12-24 hours. If severe anaemia is present '''recovery may take weeks'''.  

Haemaglobin levels should return to normal within 12-24 hours. If severe anaemia is present, '''recovery may take weeks'''.  

The original cause of the nitrate toxicity should be resolved and levels of nitrate in the water can be reduced through '''water changes, biological filtration and decreased feeding'''.

The original cause of the nitrite toxicity should be resolved. Levels of nitrite in the water can be reduced through '''water changes, biological filtration and decreased feeding'''.

Prevention involves ensuring an '''adequate levels of chloride''' in the water at all times. Most waters already have enough chloride and prophylactic treatment is unnecessary.  

Prevention involves ensuring an '''adequate level of chloride''' in the water at all times. Most waters already have enough chloride and prophylactic treatment is unnecessary.  

{{Learning

{{Learning

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[[Category:Toxicology]]

[[Category:Toxicology]]

[[Category:Fish Diseases]]

[[Category:Fish Diseases]]

[[Category:Expert Review - Exotics]]

[[Category:Expert Review - Exotics]]