MANUAL OF FISH-CULTURE. 131 



In the following season the fry were placed in pens in a pond. Confervje formed 

 in the ponds, clogging the screens, and the water got so warm that the fry, which 

 were dying rapidly, were placed in the pond with the large fish. 



In 1S93 the experiments were more encouraging. About 120,000 fry were placed in 

 a new pond, 200 feet square and from 2i to 14 feet deep, supplied with 25 gallons of 

 running water per minute at the lowest stage. Fifty thousand fry were held in a 

 small tank at the hatchery, so that their habits, food, etc., could be studied. This 

 aftbrded more instruction than all former experiments combined. Before the umbili- 

 cal sac was absorbed the fry began to take the prepared food, and as soon as the sac 

 was entirely gone they ate freely. They grew rapidly and did well until the middle 

 of May, when, the weather being very warm, the temperature of the tank rose to 

 63° F., resulting in the death of some of the fry and necessitating a removal of the 

 remaining fry to the pond containing the other fry of the same age. These fry were 

 from 1 to l^- inches long when put in the pond. They had been fed on nothing but 

 very finely divided glutin, a product of wheat, of a yellowish-white color, very even 

 in size and semi-buoyant. The floating property of this food is supposed to be very 

 important, as the whitefish when young do not feed on the bottom, which is their 

 habit when older. Any part of this food which settles on the bottom must be removed, 

 as it is liable to ferment and rise to the surface, when, if the fry eat it, they will die. 



For the purpose of removing the fry to another pond the large pond was drawn in 

 November of the same year in which they were hatched. A large seine was com- 

 pletely filled with fish at the first haul. Being. very delicate, a great many were 

 killed before efforts could be made to move them. It is estimated that nearly 50,000 

 of these young whitefish were lost. They were from 7 to 9 inches long, being about 

 8 months old. Several thousand were saved which are now (1895) 2^ years old. 

 When 2 years old 70 were caught, which measured from 16 to 18 inches long. 



When the fry are about an inch long they are fed on a stiff dough made of fine 

 middlings. This food is placed on the bottom of the tank and all that is not 

 consumed is removed. This is also the sole food of the adult whitefish. It is 

 placed in water shallow enough so that the fish-culturist may see if it is all consumed 

 during the night, the fish feeding exclusively at that time. If all is not eaten, a 

 less quantity is given for the next day, as a matter of economy and to prevent the 

 pollution of the water. 



It has been found that in the raising of fry the temperature of the water should 

 not go above 55° F., and that 65° is fatal, while fish three or four months old will 

 stand a much higher temperature. 



