FATHEAD MINNOW 



Figure 40. — Four-inch tile used for spawning devices. (Photograph courtesy of the 

 Ohio Department of Conservation and Natural Resources. ) 



adult to 40 percent immature fish. 

 Both adults and juveniles are used 

 as breeders because of the short life 

 span of the fathead. Since the 

 larger fish will die shortly after the 

 onset of spawning, it is necessary 

 to provide immature, developing 

 fish to have spawners later. In this 

 way, one can be sure of a continu- 

 ous, uninterrupted supply of newly 

 hatched fry. The brood ponds 

 should be stocked at the rate of 15,- 

 000 to 25,000 fish to the acre of 

 water. 



Spawning. — In Missouri, fat- 

 heads normally start spawning ac- 

 tivities during the latter part of 

 April or at a time when the pond- 

 water temperature reaches 65° F. 

 They spawn intermittently 

 throughout the summer, providing 

 the water temperature does not rise 

 above 85°. When this temperature 

 is reached, spawning ceases, and is 

 not resumed until the temperature 

 is lowered by prevailing weather 



conditions or by an increase in the 

 flow of spring water into the pond. 

 Sometimes, during the warm 

 summer months when the surface 

 water temperatures rise above the 

 80° to 85° F. range, the breeding 

 fatheads will conduct their spawn- 

 ing activities at lower depths than 

 normally to attain a cooler stratum 

 of water. The water at this level 

 (2 to 8 feet below the surface) fre- 

 quently is low in the concentration 

 of dissolved oxygen. Even though 

 the breeder fatheads can tolerate 

 the low oxygen content, the develop- 

 ing eggs cannot; and subsequently, 

 they all will die before the incuba- 

 tion period is completed. To coun- 

 teract this condition, the fathead 

 minnow grower must keep his 

 brood ponds free from rich organic 

 deposits, either by reducing the 

 amount of artificial food supplied 

 to the breeders, by reducing the 

 amount of fertilizer, by increasing 

 the incoming spring- water supply. 



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