204 DOMESTICATED TROUT. 



finally die. I am inclined to think, however, that the 

 disease is not always fatal, but that a change to puie 

 water and plenty of it will often effect a cure. The ap- 

 plication of earth in this disease seems injurious, rather 

 than beneficial, probably owing to the irritating action 

 of the sandy particles on the inflamed tissues. You 

 can detect the disease before death by looking directly 

 down on the fish from above. In a perfectly healthy 

 fish the gill covers completely cover the gills, and shut 

 down closely over them. In a sick fish the gill covers 

 do not wholly conceal the gills, which are visible 

 through the whole respiration of the fish, and appear 

 swollen and inflamed. After death the fish looks so 

 much like a perfectly healthy fish, that an inexperi- 

 enced person would say there was not a mark of dis- 

 ease upon it. Deaths from this cause are very pro- 

 voking to beginners, for the fish seems to them to die 

 without any cause whatever. 



1 6. Black gill fever. There is another disease of 

 the gills, which is more rapid in its action, and to 

 which I have given the above name because it seems 

 to resemble a fever, and because the gills of the fish 

 turn black. I have not had many cases of it myself, 

 but I believe it is usually fatal ; others who have ob- 

 served it think that it is contagious. I know of no 

 remedy. 



17. Fatty degeneration of the vitals. Sometimes when 

 you examine a young trout that has died without a 

 visible cause, you will find an abnormal accumulation 

 of fat about the vitals, and nothing in the stomach. 

 This is probably the cause of its death. There is, as 



