ON SOME DISEASES OF FISHES 



By G. A. MacCallum, M.D. 

 New York, N. Y. 



Through the kindness of the director, Dr. Townsend, 

 and his assistant, Dr. Osburn, of the New York Aquarium, 

 I have had the opportunity of performing several hundred 

 autopsies upon fish of many different kinds which have 

 died in the Aquarium during the last three years, and it 

 is at their request that I outline here the types of disease 

 encountered. A similar privilege has been granted me 

 by the director of the United States Bureau of Fisheries 

 Laboratory at Woods Hole, Mass., during each summer, 

 and it is instructive to compare the conditions found in 

 freshly captured, free-living fish with those occurring in 

 fish which have been for some time in captivity. Prob- 

 ably no statistical studies could be made in this way, be- 

 cause in the ocean diseased fish might not be taken in the 

 proportion in which they actually occur, either because 

 they fall out of the shoal, or because of their sluggishness 

 they are destroyed by other fish. On the other hand, for 

 the same reasons they might be taken in excess by other 

 methods of fishing. On the whole it is rare to find in free 

 swimming fish such extremely advanced diseased condi- 

 tions as are occasionally encountered in the protected 

 tanks of the Aquarium. 



My attention has been directed throughout this work 

 especially to the worm parasites of these fish and reports 

 concerning the structure and systematic relations of many 

 of these with statements as to the damage occasioned by 

 them have already been published. In addition to a brief 

 review of their influence upon fish in confinement, the 

 present paper is intended merely to indicate the general 

 character of the other diseases met with, but not really 

 studied. This may be particularly useful in showing what 

 a great field for research lies there. Of the worm para- 

 sites, which include representatives of most of the groups 

 of trematodes, nematodes and cestodes, many have been 



