Research has involved laboratory studies on the survival, development, bioenergetics and growth, swimming performance, and avoidance behavior of chinook and coho salmon, steelhead trout, and largemouth bass. Some studies have been conducted under very simple laboratory conditions, as in aquaria or other apparatus, but some studies on bioenergetics and growth have also been conducted under rather natural conditions in laboratory streams and ponds. In some important cases, close correspondence was found between the effects of reduced oxygen concentration in aquarium studies of growth at maximum rations and its effects under more natural conditions in laboratory streams and ponds. Some of the biological responses of the fish studies were affected by any appreciable reduction in dissolved oxygen below the air saturation levels, whereas others were affected only at levels below about 50 percent the air saturation levels. (Modified author abstract) Portions of this document are not fully legible.