Larval survival and growth
in Wallago attu (Bloch and Schneider): effects of light, photoperiod
and feeding regimes
S. S. Giri, S.K. Sahoo, B.B. Sahu, A.K. Sahu, S.N.
Mohanty, P.K. Mukhopadhyay, S. Ayyappan-2002
Aquaculture, 213(1-4): 151-161
Abstract:
An in-door rearing study was conducted for 11 days
with Wallago attu larvae fed on live zooplankton alone (control) or
combinations of zooplankton and dry feed containing either fish meal (F1),
meat meal (F2) or shrimp meal (F3) under 24 h continuous light (24L), 12 h
light–12 h dark (12L:12D), 24 h red light (24RL) or complete darkness
(0L). The percent survival of larvae was significantly different (P<0.05)
among the larvae reared under various light regimes with highest in 24RL,
followed by 24L, 12L:12D and 0L, in descending order. Fish fed on
combination of live plus dry feeds grew significantly faster than those fed
on zooplankton alone. There was no significant difference in growth of fish
reared under different light and photoperiod regimes when fed on live
zooplankton alone. The specific growth rate (SGR) was significantly greater
(P<0.05) in fish fed on the combination of zooplankton and dry
feeds as compared to zooplankton alone. At the end of the experiment, total
biomass production was the highest (P<0.05) in larvae reared under
the red light and lowest in the 0L treatment. Permanent darkness reduced
percent survival and suppressed total biomass production of W. attu
larvae. Red light and continuous lights promoted higher survival and biomass
production as compared to 12L:12D or 0L regimes. For highest survival and
maximum biomass production, 24 h red light exposure is suggested best during
in-door rearing of W. attu larvae.
(Fish and Shellfish Nutrition Division, Central
Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar-751002,
Orissa, India, e-mail: shibasg@rediffmail.com,
ssgiri123@yahoo.com)