HATCHING TEOTJT 153 



the sac is a work tliat should receive close at- 

 tention. Troughs must be kept clear of fungus, 

 which quickly develops whenever any of the 

 young fish die, or when filth is allowed to ac- 

 cumulate; hence not only should dead fish be 

 picked from the troughs as quickly as possible, 

 but the troughs feathered often to remove the 

 sediment or other dirt which invariably gathers 

 when feeding begins. 



After the sac is absorbed and the little fish 

 arise, a strip of wood an inch wide should be 

 added to the lower end of the troughs, so as to 

 increase the depth of the water to about three 

 inches. This will enable them to swim up 

 more freely and render the task of feeding 

 easier. 



After feeding is begun the advanced fry, as 

 they are now called, require very close attention 

 to prevent the breaking out or spread of disease, 

 especially fungus and "sore throat." The lat- 

 ter is caused generally by the fish becoming 

 weakened through an insufficient supply of oxy- 

 gen, especially when the troughs are crowded. 

 Should more than a normal mortality be noticed 

 at any time, the young fish must be given a salt 



