MANUAL OF FISH-CULTURE. 75 



a pond several modifying conditions must be considered, such as the 

 size of the fish, water supply, temperature, and shade. In stocking the 

 spawning-pond a good proportion is two females to one male. The 

 breeding stock is selected carefully every year; only sound and perfect 

 fish are retained for the next season, and the blind and emaciated 

 fish of both sexes are destroyed. 



TAKING THE SPAWN. 



The spawning season varies with the locality and the temperature of 

 the water. It is usually two to four weeks later in the streams than 

 where the fish are kept confined in spring water. In the ponds at 

 Wytheville the spawning fish may be found any time after the 1st of 

 November; the season is well started by November 15, and generally 

 closes about the 1st of March. December and January are the best 

 months. In California the season extends from the 1st of February to 

 May, and in Colorado begins early in May and continues until July. 



The natural nests of these fish are made on gravelly bottoms, and 

 are round or elongated depressions about the size of a dinner plate. 

 After the eggs have been deposited and fertilized they drop between 

 the pebbles of the nest, where they lie protected until hatched. 



Where spawning-iDonds are provided with suitable raceways the fish 

 will ascend from the ponds into them, seeking a place to make their 

 nests, and may then be taken out and stripped of their spawn. To take 

 the fish from the raceway, a square net (I, plate 22) is dropped m on 

 the cleats nailed against the side walls in the approach, shown at J, the 

 dam in the mouth of the raceway is raised, and the fish driven back 

 into tlie net. The net is then lifted out of the water, and if it contains 

 too many fish to handle conveniently a landing-net is used to take out 

 part of them before the square net is moved. The ripe fish are then 

 placed in tubs or other vessels provided for the x)urpose. If -too many 

 fish are put in the tub at one time they become restless and sick before 

 they can be stripped of their spawn. 



There are two methods of taking and impregnating the spawn of 

 fishes, the "wef and the "dry" methods. By the "wet" method the 

 eggs are taken in a pan containing sufficient water to cover them and 

 allow them to mix freely with the milt, which is immediately added. 

 After the contents of the i^an have been stirred for a few seconds with 

 a feather, the eggs are set aside and left undisturbed during fertiliza- 

 tion. The "dry" or "Russian" method is now in general use; the eggs 

 and milt are taken in a moist pan and it makes little difference which 

 is taken first, but one should immediately follow the other, and the 

 contents of the pan be thoroughly mixed. 



After the eggs and milt have had time for contact, and before the 

 eggs begin to adhere to the bottom of the pap, water is added to 

 the depth of about an inch, the eggs being kept in gentle motion, by 

 turning the pan, to prevent adhesion. After 2 or 3 minutes the milt 



