76 



net is apt to injure those on the bottom. Overloading 

 smaller nets will also produce injury and consequent 

 loss of fish. 



DISEASE CONTROL IN TANKS 



Epidemics of fungus disease will produce a large 

 loss of fish in holding tanks. While careful seining, 

 transportation, and holding of the minnows will greatly 

 reduce the chances of an epidemic starting, it may 

 happen even in the best-regulated establishments. 



At the start of the epidemic all dead fish should 

 be removed and destroyed at once. The remaining fish 

 should be dipped in malachite green 1:15,000 solution 

 (1/8 ounce in 15 gallons of water) for 10 seconds. The 

 tank must be drained and sterilized with sodium hypo- 

 chlorite i: 10,000 solution. All tools anddippers must 

 be sterilized in the same solution and must be resteri— 

 lized daily until the epidemic is over. 



Infecteid minnows should not be purchased or seined, 

 as the danger from loss and spread of disease to healthy 

 fish is too great. During times of scarcity when only 

 infected minnows are available, the fish should be 

 dipped for 10 seconds in a 1:15,000 solution of mala- 

 chite green before being placed in the holding or 

 tempering tanks. The malachite green should be dis- 

 carded after 100 pounds ofminnows have been treated or 

 at the end of the day. 



FEEDING MINNOWS IN TANKS 



Minnows that are held for more than a few days must 

 be fed. A series of feeding experiments conducted by 

 the Wisconsin Pi sh Management Division to determine the 

 effect of food on the loss of minnows in holding tanks, 

 showed that brassy minnows could beheld for 63 days at 

 46° F. with very little loss of weight when f ed all the 

 canned carp they could clean up. Fish that received no 

 food succumbed to heavy infestations of fungus, but 

 those receiving food had very little fungus. Fish that 

 received half as much carp survived nearly as well and 

 showed only slightly more loss of weight. 



Minnows will eat a variety of foods, but the most 

 practical are those that are easy to handle and con- 

 venient to store. The food should appeal to the fish 

 so that it is consumed fast enough to prevent undue 

 contamination of the tank water. Oatmeal and cotton- 

 seed meal are satisfactory foods. Meal worms, flour- 



