OPERATING THE HATCHERY 



FERTILIZING THE POND 



The object of fertilizing a pond 

 is to produce foods in large quan- 

 tities at the time they are needed 

 most by the fish. Several methods 

 of supplying fish foods are in use 

 at the present time. In the North- 

 ern States, organic fertilizers are 

 added to the pond to produce a 

 growth of bacteria and protozoa 

 (fig. 11). These small forms are 

 food for the waterfleas and rotifers, 

 which in turn are the main source of 

 food of the important bait fishes. 

 In most Southern States, the ponds 

 are fertilized with inorganic fer- 

 tilizers, which release nitrogen and 

 phosphorus into the water. Mi- 

 nute plants (algae) which often 

 give a greenish color, or bloom, to 

 pond waters utilize this nitrogen 

 and phosphorus. When they die 

 and decay the food stored in them 

 becomes available to minute ani- 

 mals (i)rotozoa) in the water. 

 These anima.ls are food for the wat- 

 erfleas and rotifers. The food cycle 

 with algae in the primary stage is 

 dangerous to use in northern ponds 

 because of the danger of an excessive 

 algal growth, which uses such a 

 large amount of oxygen from the 

 water when it decomposes that the 

 fish suffocate. 



A third method of providing 

 crustacean (waterfleas) fish foods, 

 that is little used but offers great 

 possibilities, is dry fallowing. Each 

 pond is drained and dried up pe- 

 riodically. When the pond bottom 

 is dry enough to support farm ma- 

 chinery, it is disked, fertilized with 

 10-10-10 fertilizer, and planted to 

 rye. The rye is allowed to grow to 

 a height of 6 to 8 inches before the 

 pond is refilled. As the rye decom- 

 poses a growth of bacteria and pro- 

 tozoans develops. In 7 to 10 days 

 the pond contains a crop of water- 

 fleas 8 to 10 times greater than that 

 obtained by fertilizing. Natural 

 ponds maintain their fertility by a 

 similar process. When the pond 

 level is low, the exposed bottom be- 

 comes covered with a growth of hay. 

 When the pond level is high, the 

 hay is flooded and decomposition 

 starts a new food cycle. 



For maximum growth of the fish 

 and maximum fish production, the 

 food chain should be started early 

 and should be maintained through- 

 out the growing season. In north- 

 ern ponds, barnyard manure is gen- 

 erally used in the spring because it 

 decomposes rapidly and gets the 

 food chain oft' to an early start. 

 Manure should be applied at the 

 rate of 400 to 1,000 pounds to an 

 acre of water, depending on the fer- 

 tility of the pond. Dried sheep 



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