178 DOMESTICATED TROUT. 



I. Fungus on the egg. This is the most insidious, 

 the most devastating, and the most obnoxious of all 

 the diseases of young trout, and the first in order of 

 the causes of death. It blights the embryo in the ^gg. 

 Once present in the water, it spreads unseen over all 

 the eggs, and is sooner or later fatal. The effect of 

 fungus has been already described in the chapter on 

 Hatching the Eggs, p. 115. We mention it here again 

 among diseases of trout fry, because it sometimes does 

 not kill the eggs, but causes them to produce prema- 

 turely a weakly young fish, which usually dies before 

 summer. 



