Studies on the Myxobacterium Chondrococcus

In 1922 Davis described an infectious disease which was responsible for heavy mortalities in a number of species of warm water fishes in the Mississippi Valley. Although Davis was unsuccessful in his attempts to cultivate the etiological agent, he reported that large numbers of slender, motile bacteria were characteristically present in the lesions of infected fish. He further noted that when material scraped from a lesion was placed in a wet mount, the bacteria possessed the unique property of collecting together to form columnar masses on bits of fish tissue. Because of this feature, the organism was assigned the name Bacillus columnaris, and the disease was referred to as columnaris disease. No further mention of this disease is found in the literature until the report of Nigrelli (1943) that columnaris disease had been noted in fish held at the New York Aquarium. The etiological agent of columnaris disease was isolated by Ordal and Rucker (1944) during an epizootic in young sockeye salmon (Oncorhynchus nerka) at the Leavenworth Hatchery of the U. S. Fish and Wildlife Service. Additional cultures were isolated from surface lesions and from the internal organs of adult salmon and other fishes examined at Rock Island Dam on the upper Columbia River, and from moribund adult Chinook salmon (0. tsh.awytscha) and from sockeye salmon held in large outdoor ponds at the Leavenworth Hatchery. The latter fish had been trapped at Rock Island Dam and transferred to