The Farm Fishpond 



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in obtaining them. A half dozen or more desirable kinds may be found 

 in a mill pond, a sluggish stream, or any shallow part of a lake having 

 a mud bottom. Aquatic plants are very important in the economy of 

 pond fishes, and some of the reasons for this are given as follows: 



1. They constitute the principal food of a few fishes. 



2. Directly or indirectly they furnish food and shelter to a host of 

 small organisms that are eaten by fishes. 



3. They are necessary in the spawning activities of certain fishes. 



A B c 



Fig. 199. — Pondweeds. A, Potamogeton crispus; B, P. amplifolius; C, P. helerophyllus 



4. They purify the water by taking up certain obnoxious substances, 

 including carbonic acid gas exhaled by aquatic animals, and by giving 

 back oxygen. 



5. They protect the water underneath them and the pond bottom 

 from the heat of the sun. 



Certain plants are objectionable, however, in that they decay readily 

 giving off dangerous substances, which affect the health of fishes and the 

 flavor of their flesh. There are also other plants that grow too rapidly 

 and often seriously interfere with the proper management of the pond. 

 In suggesting the following plants for the pond, the undesirable as well 

 as the desirable qualities have been considered. It must be remembered, 

 however, that certain plants may be valuable in one place and mere 

 weeds in another. 



To the Potamogetons, or pondweeds as they are generally called, belong 

 a number of forms desirable in the farm fishpond. Three common 

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