XL.-CHROMATOPHAGUS PARASITICUS-A CONTRIBUTION TO 

 THE NATURAL HISTORY OF PARASITES.* 



By Dr. C. Kerbert. 



During- the last lew months my attention has been directed to a 

 skin disease, which at first threatened to become epidemic, and which 

 affected certain freshwater fishes in the Amsterdam Aquarium. Our 

 representatives of Tinea vulgaris Cuv. (in fact Tinea vulgaris var. aurata, 

 or Tinea chrysitis Ag-dss.), Ahraniis hrania Linn., Blicca hjorkna Siebold, 

 Cyprinus carpio Linn., with the two varieties Cyprinus rex eyprinorum 

 and Cyprinus nudus, Carassius vulgaris Kroyer, Idus melanotus var. 

 miniatus Heck, and Kuerr, Trutta salar Linn., Trutta fario Linn., and 

 finally Salvelinus fontinalis Mitchill, showed all over their skjn, but 

 principally about the fins and the head and occasionally about the 

 eyes, small but very distinct milk-white round spots the diameter of 

 which varied from 0,25 to 0,0 millimeter. When these spots were ex- 

 amined microscopically, it soon became apparent that they were caused 

 by infusoria, distinguished by their enormous size. The cause of the dis- 

 ease, therefore, was evident. The disease with which we have to deal 

 here is generally termed ''spot-disease" (FleelcenJ^rankheit) by ichthy- 

 ologists and tish-culturists. 



In my opinion this so-called "spot-disease" must not be confounded 

 with phenomena observed in various other different cypriuoids by 

 Wittmack^ and other naturalists, where, on the surface of the skin, 

 there appear bluish gray spots of a slimy, fungus-like character, which 

 spread more or less over the entire body, and extend to the eyes, fins, 

 &c. This disease is termed Poclcen-Kranliheit^ or "pox," by Wittmack. 

 In his excellent work Wittmack says that possibly the real cause of the 

 disease might be traced to infusoria. I must state, however, that in 

 my examinations of fish afflicted with this disease I have so far not dis- 

 covered any infusoria. When I examined a Leueiseus erythroplithalinus 

 Linn., caught in one of the Amsterdam docks on March 31, which was 



* " Chromatophagus Parasiticus. Ein Beiirag zur Farasiteiilthre." Von Dr. C. Kerbert 

 Amsterdam, April 9, 1884. Translated from the German by Herman Jacobson, 



^Dr. L. Wittmack: ''Beitriige zur Fischereistaiisiik des Deulschen Btichs," TV, Dis- 

 eases of Fish, in Circular of the German Fishery Association, 1875, p. 187. 



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