ABSTRACT
Fish gills are responsible for several physiological activities requiring anatomic and physiological compromises. Gills being not only responsible for gas exchange, several other physiological functions that are gill exchange related, may be expressed by comparing their rates to the respiratory surface area. The transfer of gill tissue from Bouin’s to tap water showed no measurable distortion, compared with tissue transferred to an isotonic saline solution. Gill filaments from dorsal, middle and ventral portions of the each gill arch were cut off with a razor blade. When challenged with hypoxia, physiological mechanisms such as increases in gill perfusion or blood flow redistribution within the gill are likely to compensate for any impediment in gas exchange, so allowing the fish to compensate. A perfusion method has been adopted to measure the gas diffusion capacity of gills, lungs and skin. The gills of Arapaima gigas were fixed in situ in flowing glutaraldehyde and later removed to the same fixative.
