by shutting off the ponds against wild fishes, systematic, well considered manner of 

 brood grov/ing, by keeping away of fish eating water birds and by caution in the purchase 



of fishes. 



Mo other expedient can have the same high success as the prevention and control of 

 fish diseases, without increased expenditures fof the supply of food, fertilizer or 

 labor. It thereby tends to increase the yields and forms a more economic management. 



I shall emphasize in conclusion, that no fish diseases hitherto known are transfer- 

 able to human beings. All sick, but still fresh fishes which must be removed from ponds 

 for the control of parasites, may be made useable for human nutrition. 



213 



