196 DOMESTICATED TROUT. 



For causes, signs, and remedies of fungus, we refer the 

 reader to the chapter on Hatching the Eggs, pp. 127,128. 



2. Partial suffocation of the embryo. It sometimes 

 happens that the embryo will be partially suffocated 

 a short time before the egg hatches, so that, although 

 the embryo will be born alive, it will die soon after. 

 The cause of this, of course, is not giving the eggs air 

 enough, either from overcrowding them or not having 

 enough circulation in the water. The remedies are 

 obvious. 



3. Strangulation in hatching. Sometimes the em- 

 bryo dies just in the act of hatching. I have attributed 

 it to the strangulation of the embryo by the shell of 

 the egg. It may be from other causes. There is no 

 remedy that I know of, and the instances of death 

 from this cause are not numerous enough with trout 

 to make it a very serious matter.* 



4. Seth Green's dropsy, or blue swelling of the yolk 

 sac. This is a very noticeable disorder among the 

 alevin trout, and, being an affection of the yolk sac, is 

 of course confined to them. 



The sac becomes swollen to three times its usual 

 size. The outer membrane shows very thin and trans- 

 parent, is seen to be filled with a bluish liquid, and, 

 when punctured, discharges a thin, watery fluid. Seth 

 Green's book calls it the dropsy; it affects only a 



* Mr. Parnaby, of Troutdale Fishery, England, says he has 

 noticed this cause of death particularly in the char (Salmo umbla), 

 and he attributes it to the tough shell of the char egg and the 

 peculiarly round and full form of the yolk sac, which makes it 

 more difficult for the char to liberate itself from the egg than 

 for other fish. 



