DISEASES OF MARINE FISHES
13
(2) " Eye disease " of salmon, cod and other bottom fishes was also
caused by a Vibrio. The disease was characterized by initial destruction
of the eyes, followed by bacteremia and death. This malady may be
similar or identical to " Augenkrankheit " of North Sea cod (Bergman,
1912). (3) " Boil disease " was found to be a progressive and highly
fatal disease of young salmon, characterized by muscle abscesses. The
pathogen was a diplobacillus resembling the causative agent of kidney
disease of salmon in fresh water. (4) A myxobacterial disease similar
to " columnaris disease " of fresh-water salmonids was characterized
by development of gray-white lesions anterior to the tail. The lesions
progressed with sloughing of skin and fins. The myxobacterium
Chondrococcus columnaris (Davis) Ordal and Rucker, 1944, has been
described as infecting skin, gills, and fins of Fundulus hetcroclifus
(Nigrelli and Hutner, 1945) and other marine species (Davis, 1922;
Garnjobst, 1945).
This array of infectious diseases, either of salt water origin or
enhanced by salt water phases of the life history of salmon, indicates
the possibilities for disease studies in this and other anadromous fish
(Rucker et al., 1954).
Critical problems in the study of bacterial pathogens of fish, as
may be deduced from the preceding, are the correct identification of
the infectious agent and the determination of its role as primary or
secondary invader. Not only is bacterial classification confused
(Krasilnikov, 1949 ; Breed et al., 1957 ; PrBvot, 1961), but type cultures
may be unavailable, and often biochemical and physiological characterization is incomplete. Bullock (1961, 1964) has made important
contributions to the systematization of methods to identify bacterial
pathogens in fresh water and Colwell and Liston (1960), Shewan (1961,
1963), Shewan et al. (1954, 1958, 1960), and Scholes and Shewan (1964)
have attempted similar systematization for marine bacteria. Bacterial
pathogens most commonly reported from sea fishes are species of
Pseudomonas, Vibrio or Mycobacterium. Many of the bacteria normally
present in sea water, or on the surface of fish, can invade and cause
pathological effects if fish are iiijured or subjected to other severe
environmental stresses.
C. Fungi
The role of fungi in the oceans has been admirably summarized in
a recent book by Johnson and Sparrow (1961). Fungus diseases of
marine organisms received excellent coverage by the authors, and it is
startling to note that with the single exception of Ichthyophonus
hoferi (Plehn and Mu1sow)-often referred to as Ichthyosporidium
13
(2) " Eye disease " of salmon, cod and other bottom fishes was also
caused by a Vibrio. The disease was characterized by initial destruction
of the eyes, followed by bacteremia and death. This malady may be
similar or identical to " Augenkrankheit " of North Sea cod (Bergman,
1912). (3) " Boil disease " was found to be a progressive and highly
fatal disease of young salmon, characterized by muscle abscesses. The
pathogen was a diplobacillus resembling the causative agent of kidney
disease of salmon in fresh water. (4) A myxobacterial disease similar
to " columnaris disease " of fresh-water salmonids was characterized
by development of gray-white lesions anterior to the tail. The lesions
progressed with sloughing of skin and fins. The myxobacterium
Chondrococcus columnaris (Davis) Ordal and Rucker, 1944, has been
described as infecting skin, gills, and fins of Fundulus hetcroclifus
(Nigrelli and Hutner, 1945) and other marine species (Davis, 1922;
Garnjobst, 1945).
This array of infectious diseases, either of salt water origin or
enhanced by salt water phases of the life history of salmon, indicates
the possibilities for disease studies in this and other anadromous fish
(Rucker et al., 1954).
Critical problems in the study of bacterial pathogens of fish, as
may be deduced from the preceding, are the correct identification of
the infectious agent and the determination of its role as primary or
secondary invader. Not only is bacterial classification confused
(Krasilnikov, 1949 ; Breed et al., 1957 ; PrBvot, 1961), but type cultures
may be unavailable, and often biochemical and physiological characterization is incomplete. Bullock (1961, 1964) has made important
contributions to the systematization of methods to identify bacterial
pathogens in fresh water and Colwell and Liston (1960), Shewan (1961,
1963), Shewan et al. (1954, 1958, 1960), and Scholes and Shewan (1964)
have attempted similar systematization for marine bacteria. Bacterial
pathogens most commonly reported from sea fishes are species of
Pseudomonas, Vibrio or Mycobacterium. Many of the bacteria normally
present in sea water, or on the surface of fish, can invade and cause
pathological effects if fish are iiijured or subjected to other severe
environmental stresses.
C. Fungi
The role of fungi in the oceans has been admirably summarized in
a recent book by Johnson and Sparrow (1961). Fungus diseases of
marine organisms received excellent coverage by the authors, and it is
startling to note that with the single exception of Ichthyophonus
hoferi (Plehn and Mu1sow)-often referred to as Ichthyosporidium