The nitric oxide: A molecule of possible therapeutic use against aquatic stress in fishes.

In several toxicological research studies involving fish as animal model, it has been seen that fish die primarily because of suffocation caused due to dismantling of the vascular components followed by wear and tear and sloughing of epithelium layer of the respiratory organs such as gills and accessory respiratory organs (ARO) especially the air-breathing organs (ABO) found in some air-breathing fish species like Clarias batrachus, Clarias gariepinus, Anabas sp. etc. The gills are main respiratory organs and are fully aquatic in respiratory function while the ABO, on the other hand, are said to be aerial in nature i.e., extract the oxygen from atmospheric air. The ABO is hence more important for air-breathing fishes as they enable them to survive even in a condition of stress produced by ambient water contaminants/pollutants.