MANUAL OF FISH-CULTURE. 83 



learu to take their food from the bottom of the trough it is necessary 

 to feed them only three times daily, but more food must be given at 

 each meal. 



FOOD OF ADULT FISH AND YEARLINGS. 



In domestication the rainbow trout is preferably fed upon a meat 

 diet altogether, if it can be had plentifully and sufficiently cheap; 

 otherwise a mixture of liver and mush may be used advantageously. 

 The mush is made by stirring wheat shorts or middlings in boiling 

 water until the mixture becomes thick; it will keep for several days, 

 even in warm weather, if put in a cool place. The liver is ground 

 or chopped fine and mixed thoroughly with the mush in any desired 

 proportion up to four fifths of the whole, but it is better to mix 

 only as needed. This mixture has been used satisfactorily for many 

 years. 



A meat-chopper may be obtained for grinding liver which will do the 

 work in an excellent manner, leaving no strings or gristly chunks to 

 choke the fish. There are several sizes of the machine made, with extra 

 perforated plates having different-sized holes, from one-twelfth to one- 

 fourth of an inch in diameter, so that the meat may be prepared coarse 

 or fine, to suit the size of the fish to be fed. For small fry it is neces- 

 sary to use the plate having the smallest holes and to grind the food 

 over several times until fine enough to use. 



The practice of throwing food into the pond in handfuls causes the 

 fish to come together in great numbers and in a violent manner; and 

 struggling with open mouths to get a bite of the food, they often hurt 

 each other, injure one another's eyes, sometimes even plucking them 

 from the sockets. This is probably one of the main causes of blindness 

 among pond-fed fish. 



The most approved method of feeding is to walk along the pond its 

 entire length to the upper end (the fish will soon learn to follow to that 

 point), then scatter a handful of food along the surface of the pond so 

 that it will fall to pieces. The fish follow and take up what has been 

 thrown out and then return to watch for the next handful, and the 

 operation is repeated until sufficient food is given. This manner of 

 feeding induces all the fish to head in the same direction while eating, 

 thus reducing the danger of injury. 



The amount of food for a given number of trout depends upon the 

 size of the fish and the temperature of the water, as fish will not take 

 food as freely in a low temperature as they will in warmer water. 

 With water from 50*^ to 60^ a daily ration for 1,000 yearling fish ranging 

 from 3 to 5 inches in length is about ^ of a pound; while for the same 

 number, 8 to 12 inches long, about 12 i)ounds per day are required. 



As the fish increase in size the amount of food should be increased 

 proportionately. They are fed twice a day at regular hours, morning 

 and evening, giving half of the daily allowance each time. This keeps 

 them in a thrifty and growing condition. 



