102 >^^EW YORK ZOOLOGICAL SOCIETY. 



that from brooks. Its value for pond supply will be improved, if 

 it can be led some distance as a rivulet. 



Fish-life in small ponds with limited water supply will sufifer 

 from heavy ice in winter. The ice should be broken daily, and 

 masses of brush and branches placed partly in the water will aid 

 in keeping air holes open, especially if they are moved by the 

 wind. 



Extent and Depth of Ponds. — The extent and depth of ponds 

 made by damming streams, will be governed somewhat by the 

 nature of the situation available. 



A pond of an acre or more in extent, and with eight or ten feet 

 of water in the deepest part, will, if properly managed, give ex- 

 cellent results. It may be necessary to make it less than one- 

 quarter of an acre in extent, but a small pond should have an 

 extreme depth of not less than six feet, although it is quite pos- 

 sible with a strong water supply to raise fishes in very small and 

 shallow ponds. This, how'ever, means active cultivation, with 

 daily feeding of the fishes, numerous ponds to permit of sorting, 

 and all the details of a fish-cultural establishment. As a matter- 

 of-fact, nearly all of the extensive fish-breeding carried on by 

 the National and State fish commissions has been done in ponds 

 of rectangular shape, averaging perhaps less than loo feet in 

 length and 25 feet in width, having depths of only three or four 

 feet. Such ponds are worked in series, as nursery and rearing 

 ponds, and there are generally two or more ponds of large size 

 in which fishes of dififerent growths can be held. 



The following extract from the report of the fish commissioner 

 of Indiana for 1903-04, is worth inserting in this connection : 



"Mr. Carl H. Thompson, of Warren, Indiana, has a fish pond 

 60 x 120 feet in surface dimensions, and from four to six feet 

 deep. In May, 1895, he placed in this pond four pairs of small- 

 mouthed black bass. Fifteen months later he seined the pond and 

 took therefrom, by actual count, 1.017 black bass averaging one 

 pound each. In addition to the above he took between six and 

 seven hundred yellow perch, weighing, according to his statement, 

 'not less than 250 pounds.' This makes the production of the 

 pond amount to 1.267 pounds for a period of fifteen months." 



The whole subject of fish-culture of this character — carried on 

 in small excavated ponds, will be found, discussed at length, in 

 the "Manual of Fish Culture." referred to later. 



Ponds to be used for black bass and in fact most other fishes, 

 ought to be several acres in extent and quite deep. In general. 



