104 FISH CULTUEE 



Raceways. — There has been a tendency in 

 recent years for fish-culturists to abandon race- 

 ways, owing to a well grounded belief that 

 ponds in nests or groups yield better results; 

 but wherever ponds are built separately I would 

 advise the making of raceways, even if they be 

 not intended for the use of spawning fish, be- 

 cause thus the shallow, rapidly running water 

 becomes well aerated before entering the pond. 

 Where the supply of water is not scanty, the 

 raceway might be from three to five feet wide, 

 not less than 20 feet long, and with a depth of 

 from six to eight inches. The bottom should be 

 thickly covered with clean coarse gravel, both 

 for aerating purposes and to attract the fish 

 from the ponds when they are ripe enough to 

 spawn. The sides must be of carefully set 

 boards, concrete, or building-tile, and so ar- 

 ranged that the whole raceway can be covered 

 from end to end in order to exclude the light 

 during spawning season. At the upper end or 

 entrance there must, of course, be a screen to 

 prevent the fish from going past a certain point 

 or into the pond above. At the bottom there 

 should be a gate, kept open except when the 



