Importance of Diet Type, Food Particle Size, and Tank Circulation for Culture of Lake Hallwil Whitefish Larvae
C.A. Enz, E. Schäffer, R. Müller-2001
North American Journal of Aquaculture, 63(4): 321-327
Abstract:
A commercial dry diet and both live and frozen
zooplankton were compared as food for cultured larvae of Lake Hallwil
whitefish Coregonus suidteri during the first 3 weeks after hatching.
Whitefish larvae fed live zooplankton grew considerably larger (16.4 mm
final length) than those fed frozen zooplankton (14.4 mm), but mortality did
not differ significantly (0% versus 3%). Larvae fed the dry diet reached
nearly the same length (13.6 mm) as the fish fed frozen zooplankton.
However, mortality of fish fed the dry diet was significantly higher (34%)
than that of fish fed live or frozen zooplankton. We conclude that diet
acceptance is a key factor for whitefish larvae, accounting for the highest
growth rates by larvae fed live zooplankton. We also tested the effect of
two additional factors on larval mortality: food particle size and water
circulation in the rearing tanks. The size of food pellets was reduced from
200–400 µm to 100–200 µm. The water inflow to the tanks was placed
below the water surface to increase the time the dry diet was afloat. Our
results showed that neither particle size nor inflow placement affected
mortality when fish were fed ad libitum. Nevertheless, feed floating times
were prolonged significantly when the inflow was placed below the water
surface, making it possible to decrease the feeding frequency, reduce food
losses, and, thus decrease the amount of daily ration fed.
(Swiss Federal Institute for Environmental Sciences
and Technology (EAWAG), CH-6047 Kastanienbaum, Switzerland