Fish Hatchery Management - fisheries & aquaculture

NU]'RITION AND FEEDINGis distributed in the trough.by automatic feeders set to feed at 5-minute intervalsfrom dawn to dusk (Figures 75 and 76)-Coolwater fish will not pick food pellets off the bottom of the tank so itis necessary to continually present small amounts of feed with an automaticfeeder. In some situations, coolwater fry are started on brine shrimp andthen converted to dry feed. Pennsylvania workers rePort that muskellungeare extremely difficult to rear on artificial feeds. However, the tiger muskie(northern pike male x muskellunge females) adapts readily to dry feeds.Northern pike will accept a dry feed and also adapt to culture in tanks.Walleye fry have been observed feeding on the W-7 diet, but did notsurvive well on it. Anemia developed in advanced fingerlings, indicating adeficiency of some nutrient.Tiger muskie fry aggressively feed on dry feeds. Fry often follow a foodparticle through the entire water column before striking it. Hand-feedingor human presence at the trough does not disrupt feeding activity. However,when the fish attain a length of 5-6 inches, human presence next to atrough or tank can disrupt feeding activity completely. cannibalism generallyis a problem only during the first 10-12 days after initial feeding,when the fish are less than 2-3 inches in length. The removal of weak anddying fry greatly reduces cannibalism.The methods developed for estimating feeding rates for salmonids can beadapted for use with coolwater species. Michigan workers use a HatcheryConstant of 40 to calculate feeding rates for tiger muskellunge raised in70"F water.Feeding Guides forWarmwater FishesCATFISHNewly hatched catfish fry live on nutrients from the yolk sac for 3-10 days,depending upon water temperatures, after which they accePt food from avariety of sources. Generally, feed for trough-feeding of fry should be smallin particle size, high in animal protein, and high in fat. Salmonid rationsare well suited for this purpose. Palatability of lower-quality feed isenhanced by having a high percentage of fish meal, fish oil, chopped liver,egg yolk, or other ingredients that serve as attractants.bverfeeding in the troughs should be avoided and adequate water flowsmust be maintained to avoid fouling the water. The fry should betransferred to ponds with high zooplankton densities as soon as possible toefficiently utilize the natural food source'Supplemental feeding of fry in ponds should begin soon after stocking. A