FATHEAD MINNOW 



day how much food is to be applied 

 to eacli pond. If the plankton 

 bloom remains about the same in the 

 water from day to day and the fish 

 are growing, then the amount of 

 food is sufficient. If the plankton 

 bloom becomes too intense and the 

 fish continue to grow, then he is 

 feeding too much; or if the fish are 

 not growing, the amount of food is 

 too small. At the end of the grow- 

 ing season, a successful propagator 

 should not have used more than 1 

 pound of food for each 20 pounds 

 of fish in any 1 day during the peak 

 of growth. Also, if his operations 

 were successful, he should not have 

 used more than 6 pounds of food to 

 produce 1 pound of salable fat- 

 heads. 



When about 50 percent of the fat- 

 heads (by weight) in a growing 

 pond attain salable size (11/2 inches 

 or more in total length), it is de- 

 sirable to remove as many as pos- 

 sible by trapping, seining, or by 

 draining the pond, and to place the 

 fish in a pond by themselves. To 

 drain a fathead pond during the hot 

 summer months, it is necessary to 

 pull the water level down to about 

 1/5 of its original volume and to 

 triple the incoming flow of cool 

 water, or, at least, to increase the 

 flow until all of the w^ater remain- 

 ing in the pond has a temperature 

 below 80° F. If the water tempera- 

 ture in a pond cannot be lowered to 

 this extent, it is better to seine or 

 trap out as many of the salable fish 

 as possible and to leave the others 

 in the pond, rather than to run the 



risk of losing most of the fish by 

 trying to get them all out. 



Extensive culture of fatheads 



The extensive culture of fathead 

 minnows employs the use of much 

 larger ponds than are used in in- 

 tensive culture. Locating the site 

 for a hatchery of this type is rela- 

 tively easy, since the water supply 

 is not too important ; however, it is 

 necessary to locate the hatchery on 

 soil that is composed of a tight clay 

 loam capable of holding water. The 

 source of water is provided by rain- 

 fall, and the ponds are strategically 

 located to pick up surface runoflf. 

 The design of the hatchery usually 

 follows a characteristic pattern. It 

 consists of one or more large (20 to 

 30 acres in surface area) reservoir 

 ponds having a maximum depth of 

 15 to 20 feet, surrounded on the 

 lower-gravity side by several small 

 (14- to 1-acre) ponds. 



The smaller ponds, in turn, are 

 filled with water acquired by grav- 

 ity flow from the larger pond above. 

 In instances when the annual rain- 

 fall is not sufficient to fill the reser- 

 voir ponds, some operators resort to 

 the use of a pumping system, ob- 

 taining their water from a nearby 

 stream. The large reservoir ponds 

 usually have a bottom drain and an 

 emergency high-water overflow\ 

 The small ponds are supplied w4th 

 water from the large ponds by 

 means of a series of contour ditches. 

 Very few of the smaller ponds have 

 bottom drains, and the operator 

 must cut a hole in the levee to drain 

 the pond, siphon the water out, or 



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