cifri annual report 2007- 2008 - Central Institute of Brackishwater ...

of 25mtn to raisc table fish from adv;~nce fingerling.
Fingerlings of only C. catla were stocked at different
dcnsitics at different stocking density to study their
growth pcrfbrniance. Fishes in each cage wcrc fed
with rnixturc of mustard oil cake and rice bran l~d
libitum in a suspended tray at sub-surfacc zonc.
indicating their breeding scason. Thc ftcundity of'the
fish nlngcd from 530 (fish; 29.2~111; 437~) to 2419
(lish: 29.8~1~1: 49 I g). 'TIIc highc~t Scc~~nclity was 4
rccordcci during August, but higher \faluc \vah also
rccoraad during Octobcr.
During 60 days trial, the data indicated that fish
growth was dcnsity dependent with rnaximutn growth
(310'Y") at lowcst density. However, the growth
perfomiancc plateaued up to stocking dcnsity of 3 m '
followed by drop in growth as the density of stocking
was incrcascd.
While improving the fish yield from wetlands through
stock enhancement is acceptable but keeping the
balancc hctween indigenous and cxotic species in thc
stocking watcrs is important from biodiversity angle.
In these water bodies cxotics have to be kept undcr
control. In this con tcxt breeding population of tropical
South Amcrican Snilfin catfisll bclonging to filniily
Loricariidac was recorded in Ciornokpota fishery
under East Calcutta Wctlands. A hugc biomass,
approxirnatcly 20 metric tones was harvcstcd in a
single month during February, 2007, from the said
wetlands. The two species identified wcrc
Ptc~n~opliohtl7v.v di.~jlill~til'~~ and f: parrlrli.~. Gut
contents analysis indicated, the spccics is dctritivore,
sincc morc than 95% of the content was occupied by
detritus.
Gravid females with mature ova and presence of
young fishes indicatcd the existence of breeding
population.
The spccics is a prolonged brccdcr.
Maturc ova were noticed from July till October