256 



FISH HATCHERY MANAGEMENT 



Table 31. initial feeding times for various species of fish. 



REMARKS 



Brown trout 



Cutthroat trout 



Rainbow trout 



Channel catfish 



Tiger muskie 



Northern pike, 

 walleye, 

 muskellunge 



31 



23 



20-30" 



at swim-up 



at swim-up 



Several fry had food in gut on 

 23rd day; all fry were feeding 

 on the 35th day. 



52 Evidence of food in stomach on 



27th day; all fry feeding on 31st 

 day. 



47-51 Evidence of food in stomach on 



14th day; all fry feeding on 23rd 

 day. 



47 Evidence of food in stomach on 



21st day (16 days at 50°F). 



— 5 to 10 days after hatching, 



depending on water tempera- 

 ture. 



68 Food presented at swim- up; most 



of yolk sac absorbed after 8 

 days. 



50-70 Food presented at swim-up, up to 



12 days post-hatching. 



Various reports include a range of initial feeding times and water temperatures. It is 

 important to note that in some instances, evidence of food in the stomach did not occur until 

 several days after swim- up. 



Table 32 presents feeding frequencies for trout and Pacific salmon finger- 

 lings. 



Successful feeding of dry feeds to coolwater fishes, such as northern pike 

 and tiger muskie, requires initial feeding of fry at 5- minute intervals, at 

 10-minute intervals when fry are 2 inches long, and at 15-minute intervals 

 when they are 4 inches long, from automatic feeders during the daylight 

 hours. 



A rule of thumb used by some fish culturists is to feed iJo of the body 

 weight per feeding. Therefore, if the fish are being fed at a rate of 10% of 



