Respiration in An Air-Breathing Fish, The Climbing Perch Anabas Testudineus Bloch

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Abstract
1. Respiration of the climbing perch Anabas has been studied under five different experimental conditions. (a) The mean O2 consumption of a fish allowed free access to air, is about 113 c.c./kg/h at 25°C. The fish obtain nearly equal amounts of oxygen through the gills and through the accessory organs. (b) The overall O2 consumption from water of a fish allowed free access to nitrogen is nearly the same as during normal respiration from water with access to air. (c) The O2 consumption is reduced when the fish is out of water and obtains all its oxygen from air. (d) The O2 consumption from air increases considerably when the fish is maintained in de-oxygenated water and depends upon surfacing for its oxygen supply. (e) The O2 consumption of a fish kept in aerated water and prevented from surfacing remains at a minimum level relative to the other four conditions. 2. Much more carbon dioxide is released through the gills than through the accessory organs (10:1) when the fish respires from aerated water with access to air. The accessory organs are much more important for O2 uptake. 3. The respiratory quotient is approximately 1 when the fish is in aerated water, with or without access to air, but is only 0.7 when the fish is out of water. 4. Anabas can live out of water for 6-10 h if protected from dehydration. It continues to breathe quietly in air-saturated water using its gills alone for shorter periods (6-8 h) when denied free access to air.