RELATION OF CERTAIN AQUATIC PLANTS TO 

 OXYGEN SUPPLY AND TO CAPACITY OF 

 SMALL PONDS TO SUPPORT THE TOP- 

 MINNOW (GAMBUSIA AFFINIS) 



By R. L. Barney^ Director 

 and 

 B. J. Anson, Scientific Assistant 

 U. S. Fisheries Biological Station, Fairport, Iowa 



In attacking the broad and complex problem of furnishing 

 fish with those conditions which best fulfil their requirements 

 for growth and propagation, there are three considerations 

 of paramount importance. These have been well discussed in 

 a recent publication by Dr. R. E. Coker,* U. S. Bureau of 

 Fisheries, who suggested therein as the biologically fundamen- 

 tal factors governing the success of fish-cultural enterprises, 

 the provision of sufficient oxygen, the provision of sufficient 

 food, and the proper association of species. Much is known 

 generally of each of these necessities; comparatively little ex- 

 perimentally. A fish culturist and a stock raiser know very 

 well that their charges require plenty of oxygen and plenty 

 of food if they may be expected to attain maximum size and 

 maximum productiveness. The stockman takes no thought of 

 the first factor, knowing that oxygen for his purpose is as 

 free as the air, whereas, for the fish culturist, such a condition 

 does not always exist. 



There is, too, the relatively larger consumption and possible 

 utilization of all the oxygen in the fish pond, since depletion 

 of this life-supporting element occurs from the chemical oxi- 

 dation of much material in the water, as well as through 

 consumption by the respiration of aquatic animals. To be 



*Coker, R. E.: Principles and problems of fish culture in ponds. The Scientific 

 Monthly, Vol. VII, No. 9, August, 1918. Garrison, N. Y. 



