nitrite
A brief consideration of effects, adverse, limits and experience of aquarists taking into account available on the web Sources.
symptoms of nitrite load:
nitrite blocked the transport of oxygen in the blood of the fish.
formation and effect nitrite blocked the transport of oxygen in the blood of the fish.
- The fish are under the surface
- gasp for air.
- increased respiratory rate
produced in the aquarium from the ammonia / ammonium NH 3 / NH 4 the nitrite by bacteria. There are bacteria of the genus Nitrosomonas oxidize and the other the ammonium / ammonia to nitrite. The effect of nitrite as a poison is based on two mechanisms:
methemoglobin
Similar to the human red blood cells, the oxygen is bound by the hemoglobin. It binds to the divalent iron in hemoglobin. However, if the Fe II is oxidized to Fe III, it loses its ability to bind to oxygen, then we speak of methemoglobin. This process of oxidation of the central iron atom is practically constant, so that a certain proportion of the hemoglobin is present physiologically as methemoglobin. Only if this proportion exceeds a certain threshold the oxygen supply to the problem. This threshold is species specific, however, fish have to live with greater fluctuations in the oxygen content in the water here has a higher tolerance. The organism has a repair mechanism of the enzyme methemoglobin by reduced back to hemoglobin (methaemoglobin). Nitrite is so vital to a problem only when the oxidation of hemoglobin exceeds the reduction of methemoglobin.
osmoregulation
Part of the osmoregulation of the fish is done via the Ionocyten (chloride cells) in the gills. On these cells is different chlorides on the fish out of water, which he excretion lost through the kidneys. These chlorides now competes and the nitrite enters the blood. The fish depleted of chlorides. The nitrite can now be in the red cells, in transport in the erythrocytes of certain cells similar to the chloride cells play an important role. The red blood cell loses potassium and also shrinks. Which of these two causes
plays the decisive role, or whether both will co-operate lethal reserved for future studies.
way into the fish
As the nitrite was reached in the fish and the red blood cells already mentioned above. There are probably several ways:
this theory is probably now obsolete,
this is probably the most effective way
The body also has mechanisms to neutralize the nitrite by enzymatic oxidation to make as nitrate.
discussion of limits
to limit values for the nitrite can be little concrete in the literature or the Internet, place, and the Mergus are in Volume 1 1.0 mg / l for Poecilia reticulata, it's in the Lewis and Morris found work as an aquarium fish Gambusia affinis, its value is 1.5 mg / l. Krause (Handbook of aquarium water) writes that are tolerated under favorable conditions for several days of 2 mg / l.
found in various (business) brochures and instructions how to nitrite test, different values of 0.5 over 0.8 to 1.0 mg / l. In the literature, a similar spectrum refers to "limits". Next are my recommendations on the internet aware of Gerd Kassebeer at values of about 0.3 mg / l sees action or Ralf Rombach of its limit at 0.5 mg / l provides both supply but no Justification for these values. I myself can out of me, cared for aquariums over values greater than 3 mg / l nitrite (measured with tetra nitrite test) report, which resolved without damage.
importance for the aquaristic practice: fish with high oxygen demand such as fish from very warm waters and fish with an adaptation to very oxygen-rich waters are very much more sensitive to nitrite, this effect can be chloride-poor water (eg reverse osmosis water or demineralizer water) reinforced be. Fish from the same habitats show different responses to nitrite. Nitrite competes with the oxygen and chlorides to the uptake via the gills in the fish. Sufficient Oxygen levels and chloride in the water make it difficult to inclusion of nitrite. Also, the pH and the dissociation of HNO 2 probably plays a role. Since the toxicity of nitrite is dependent on these factors is the concentration in aquarium water not an indicator of toxicity.
Conclusion
nitrite should be kept as low as possible. A certain concentration of nitrite in the aquarium is required. The often required in Internet forums is null or nn (not detectable) is practical and factual nonsense.
Increased nitrite value in the current aquarium is a signal for increased attention and careful observation of the fish and search for the cause. Latest at levels above 0.5 mg / l should react and affect our water intake, the relevant parameters, earlier in soft water aquariums may. The addition of sodium chloride (table salt) can mitigate the harmful effect.
literature and web links
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