OPERATING THE HATCHERY 



zation of the treated area will as- 

 sist in producing a waterbloom, par- 

 ticularly if the vegetation is heavy. 



2,4-D 



In the use of 2,4-D, it is essential 

 that a uniform application be made 

 on the treated area and that all 

 plants be thoroughly wet. Under 

 these conditions, usually about an 

 80- to 90-percent kill results, and a 

 second application must be made 

 wherever new shoots appear. This 

 may be followed by an occasional 

 shoot appearing that can be pulled 

 by hand. 



SPRAYING EQUIPMENT 



Many sprayers are on the market 

 that can be used to spread these 

 chemicals. If considerable use is 

 to be made of such equipment, it 

 probably would be ad\nsable to 

 have a sprayer that can be mounted 

 in the back of a truck. There are 

 many pieces of equipment on the 

 market designed for specific jobs. 

 Large dealers handling farm equip- 

 ment or garden supplies can recom- 

 mend the proper piece of equipment 

 for your specific needs. 



CONTROLLING DISEASES 

 AND PARASITES 



When raised in ponds, minnows 

 can be expected to suffer from many 

 of tlie diseases of hatchery fishes. 

 For this reason, it seems wise to 

 mention some of these diseases and 

 parasites, and to outline briefly a 

 program for their prevention and 



cure. Moreover, diseased and ail- 

 ing fish are often collected by un- 

 suspecting dealers, or the fish may 

 become fungused from improper 

 handling in the nets or tanks. 



The best method of disease con- 

 trol in a hatchery is prevention. 

 Fish that are handled properly and 

 that are adequately "tempered" be- 

 fore handling will usually be free 

 from disease. 



Bait fishes are infested by several 

 kinds of parasites, and the follow- 

 ing numbers of species have been re- 

 ported from them : 



Number of 

 parasites 



White sucker 20 



Golden shiner 14 



Bluntnose minnow 9 



Western mud minnow 4 



Common shiner 3 



Fathead minnow 2 



Silvery minnow 2 



Most of these parasites will not 

 cause loss, and only a few are char- 

 acteristic enough for the hatchery- 

 man to recognize. Most likely to 

 cause considerable loss in bait fishes 

 are fungus diseases, fin or tail rot, 

 black grub, and certain other dis- 

 eases that are discussed in succeed- 

 ing pages. 



WHEN TO TREAT 



In any method of treatment, time 

 is of vital importance. Disease rap- 

 idly lowers the vitality of small fish, 

 and although today they can with- 

 stand the rigors of treatment, to- 

 morrow may find them too weak. 

 The fish culturist must maintain 

 strict watch on his stock. Early 

 warning of the presence of many 



50 



