2 20 TWELFTH ANNUAL REPORT OF THE 



sickness which the fish overcome in which the ulcers leave visible scars. 

 The epidemic is especially severe where the aeration of the water is deficient. 

 It may well be conceived that in such case the disease is most deeply fixed, 

 and not only doss it appear in such ponds, but it spreads from the diseased 

 fish to the healthy ones and even from one pond it is carried through the 

 water to another pond. 



The greatest care is necessary in feeding the fish to avoid this disease. 

 Foul remains of food must be carefully removed. Therefore the trout 

 ponds must be covered only by a clean gravel or sand bottom and not by 

 humus or mucky bottom. The bottom, of course, can be dried out and 

 made sanitary by drainage. 



The introduction of seeds in great quantity which is practiced by the 

 fish breeders in carp ponds must be strictly avoided in trout waters. Infected 

 ponds must be perfectly disinfected with quick lime, which should be used 

 in such quantity as to make the entire water of the pond cloudy like milk. 

 Through the corrosive action of the lime hydrate, which is to be left in the 

 pond fourteen days, all the bacteria are killed. Drying out and winter 

 freezing of the pond bottom and of the banks are also necessary, but they 

 are not always effective. 



Curing the ulcerated brown trout or brook trout is not usually possible. 

 Diseased fish should be removed and destroyed by boiling. This is not 

 absolutely necessary, but it is very advantageous. In the case of a mild 

 form of the disease, it is possible to secure a recovery of the fish if they are 

 placed in a rapid current of cold water in which, obviously, a spread of the 

 infection is very difficult. 



Translation from Dr. Hofer — pages 4 et seq. 



The Spot Disease of the Brook Trout. 



(Hofer, Handbuch der Fischkrankheiten, pp. 33-34). 



In our fish culture establishments, especially at spawning time, the 

 American brook trout, Salmo fontinalis, has suffered greatly from a peculiar 

 disease which is so virulent that most of the fish sustain great damage, 

 so much so that some fish culturists, solely because of repeated occurrences 

 of this disease in their stock, have entirely given up the breeding of brook 



