26 



determine the amount of fertilization is to keep the 

 water colored so that a hand is not visible at the 

 depth of 1 foot. Artificial feeding and fertilization 

 should be done at the optimum rate because excess 

 fertility in the pond not only wastes the food or 

 fertilizer but will endanger the oxygen supply. 



When soft-water ponds are fertilized, it will be 

 necessary to add agricultural limestone to the water 

 to maintain proper alkalinity, A rule-of-thumb for 

 liming ponds is to add half as much limestone as 

 fertilizer, 



FEEDING THE MINNOWS 



The alternative to fertilization is artificial 

 feeding of the fish. The usual procedure is to feed 

 the fish all the ground food they will eat in 2 hours. 

 Ponds operated under arti ficial feeding have such large 

 populations of fish that food cannot be allowed to 

 remain longer than2hours without danger to the water's 

 oxygen supply. One successful food formula contains 

 15 percent cottonseed meal and meat scraps mixed with 

 85 percent of middlings. Another formula contains 100 

 pounds of beef melts, 50 pounds of dry dog food, 50 

 pounds of whitefish meal, 6 pounds of salt, and water 

 enough to make a good feeding consistency, Piftypounds 

 of carp can be substituted for 25 pounds of fish meal. 

 A formula that produced large numbers of minnows in 

 Michigan is mixed as follows: 



Product Pounds 



Cooked cornmeal and oatmeal ■ 275 



Bone meal 200 



Clam meal 400 



Maggots can be provided byputting fresh— meat scraps in 

 a screen-bottomed box, which is placed over the pond so 

 that the maggots can fall into the water. 



Many minnow ponds will produce a large number of 

 crayfish from natural stock that either migrates into 

 the pond or hibernates in the pond bottom. Some species 

 dig so deeply into the soil that draining the pond does 

 not kill them. In many localities the crayfish can be 

 sold for bait (p. 78 ), but where there is no demand, 

 ground crayfish make excellent minnow food. Such food 

 is usually available only at the fall harvest time, but 

 it can be fed to the fish in winter holding-ponds or 

 used for fertilizer on the pond bottom. Crayfish can 

 be controlled by the use of crayfish traps baited with 

 meat. 



