882 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Such brooks, coming from a neighboring hilly territory or from mount- 

 ains, will frequently occasion an overflow if either a thunder-shower or 

 sudden thawing of snow and ice should set in ; in the latter case the 

 ground might be too hard with the frost to allow the water to run off 

 readily. 



If the overflow should even be inconsiderable it would still exercise 

 an injurious influence upon the fishes, as the influx of so much water, 

 which in all probability would contain unfavorable substances, would 

 be apt to drive them from their winter retreat. 



In summer, sudden, violent rain-showers may cause an overflow 

 within a few minutes, which will carry off the fishes, and eventually may 

 destroy all the ponds. To secure against this, the construction of re- 

 serve-sluices, such as are contrived in artificial ponds, and a wide re- 

 serve-ditch alongside the pond, which is destined to carry off the threat- 

 ening high water, are recommended. A small dam between the pond 

 and brook, instead of the reserve-ditch, will sometimes answer. 



Great caution is necessary in the selection of the site for a pond or 

 the natural pond, which is to be converted into a carp-pond. 



Overflows not only injure the ponds and fishes, but may result in a 

 still worse disaster, that of carrying away the fishes into strange waters 

 and destroying the ponds. 



The fundamental rule in carp-culture is that the water be of the same 

 depth in summer and winter. If the supply of water is too plentiful, 

 great quantities of mud are carried into the pond, embedding the grass 

 which grows in it and on its banks ; this, in consequence, will rot and 

 poison the water. The carp immediately desert such water on account 

 of its offensive odor and retire from their proper feeding-places to depths 

 deficient in the production of food. 



The mud, which is being constantly reproduced, consists of the re- 

 mainders of plants. From these different gaseous compounds develop 

 themselves in midsummer, and the fishes become sickly in consequence. 

 In this case, especially if they rise to the surface seeking for air, more 

 water must be supplied through the inlet-sluice, when they will re- 

 cover by degrees. A casualty of this description may occur in very 

 large ponds, though no overflow may have taken place. 



Pernicious gases develop themselves from the mud even in winter, but 

 they rarely have any bad effects, being injurious only if the water is 

 covered by ice, when the fishes die from suffocation. For this reason 

 large apertures are cut into the ice for the supply of fresh air, 



4.— Stocking the ponds and care of the fishes. 



To carry on carp-culture in a regular and judicious manner, several 

 ponds are required, according to the various purposes they are destined 

 for. 



