Technical Bulletin No. 0133: Progress Report on Dissolved Oxygen Tolerance of Largemouth Bass and Channel Catfish at 25 and 35 Degrees Centigrade

The attached Technical Bulletin first issued in 1960 reports on the continuation of research, dealing with the dissolved oxygen tolerance of fish species common to southern waters, conducted by the National Council's University of Georgia Aquatic Biology Project. Largemouth bass and channel catfish were the organisms employed in the test work which was conducted at temperatures of 25°C and above to simulate conditions existing seasonally in southern streams. Both acclimation tests, in which the dissolved oxygen content of the water containing the fish was gradually lowered, and shock tests, in which the fish were subject suddenly to low oxygen levels, were run. Both species of fish were found able to survive shock dissolved oxygen levels of below 1.8 ppm at temperatures of as high as 35°C. Fish acclimated to low dissolved oxygen levels survived at levels between 0.83 and 1.24 ppm under similar temperature conditions. The results of this research explain many of the observations made in the field with respect to dissolved oxygen levels and fish survival, and should continue to be of service as a guide in establishing dissolved oxygen requirements under specific stream conditions.