A 2-year study of the composition of bottom fauna, its seasonal and annual variations, and its utilization by hatchery-reared rainbow trout was made in experimental stream channels of Convict Creek, Mono County, California. Three orders of aquatic invertebrates, Trichoptera, Coleoptera, and Ephemeroptera, comprised 70 percent of the total bottom fauna. Terrestrial insects were an important food source between June and November but were absent from the diet between December and February. Forage ratios and frequency of occurrence of the primary food organisms is given. Post-hatchery survival of rainbow trout in small high altltude streams appears to be more dependent upon the physical condition of the trout at time of stocking than on a highly favorable physical environment.

In epizootics of channel catfish virus diseasse (CCVD) at four widely separated fish farms in 1968, affected fry and fingerlings spiraled, hung in a vertical position with head at the surface, or were distressed. In various combinations were edema, hemorrages, and anemia. The disease had a peracute to acute course, and stress to the fish preceded most epizootics. The virus induced formation of syncytial cells in affected cultures, which is considered at present to be of diagnostic significance. Secondary bacterial infections were found in fish with CCVD. Columnaris infection masked the symptoms of the virus disease.

The 1970 fall chinook salmon feeding trials indicated that dry pelleted diets were equal to moist pelleted diets with similar formulations. A superior diet was produced by reducing the ratio of dried whey product and wheat germ meal to 1:1 and eliminating cottonseed meal. This formulation feed at a 45-percent protein level was more efficient than other protein levels fed. Growth was not reduced when the soybean oil supplement was lowered from 6 to 2 percent of the diet. Two corn distillers' products that were substituted as partial replacements for dried whey product did not enhance fish growth. Storage of the Abernathy dry pellet at room temperature did not alter the nutritional adequacy of the diet.

Feeding trials using fall chinook salmon finglerlings were conducted at the Salmon Cultural Laboratory, Longview, Washington, during 1971 for the purpose of improving the Abernathy diet formula. The results indicated that cottonseed meal could replace a portion of the fish meal in the diet without reducing fish growth, but similar substitutions of wheat and corn gluten meal reduced growth. Fish growth was significantly increased when a diet containing 50 percent protein and 3,350 kcal per kilogram was fed as compared with a diet containing 45 percent protein and 3,350 kcal per kilogram. Soybean lecithin proved to be equal to soybean oil as a caloric source when fed at 2 percent of the diet. Two types of dried whey product with different levels of lactose content produced similar growth response. Reducing the dried whey portion of the diet to 5 percent did not affect growth, nor did methionine supplementation produce any effects. Anchovy meal was unsuitable as a replacement for herring meal.