Abstract
In the freshwater area of Vietnam’s Mekong Delta,
Barbodes gonionotus (Bleeker), Cyprinus carpio L. and
Oreochromis niloticus (L.) are often reared together in
rice ¢elds. The survival rate and speci¢c growth rate
(SGR) of C. carpio showed a large variance. To understand
the underlying reasons for this variation, we
used multiple regressions for the variables SGR and
survival rate, using the results of eight experiments
in such polycultures at the Co Do rice^¢sh experimental
station. The SGR of C. carpio declined with increasing
rice density. Interspeci¢c competition with
O. niloticus also had a negative e¡ect on C. carpio
SGR.When fertilizer ormanure is added to the trench
of the rice^¢sh ¢eld or when extra food can be given
to the ¢sh, O. niloticus seems more appropriate than
C. carpio. The survival rate of C. carpio depended on
season, C. carpio stocking weight and density and
the biomass of wild ¢sh species.To obtain higher survival
rates, one should stock fewer ¢sh but of a larger
size, after thorough eradication of wild ¢sh species.
AbstractIn the freshwater area of Vietnam’s Mekong Delta,Barbodes gonionotus (Bleeker), Cyprinus carpio L. andOreochromis niloticus (L.) are often reared together inrice ¢elds. The survival rate and speci¢c growth rate(SGR) of C. carpio showed a large variance. To understandthe underlying reasons for this variation, weused multiple regressions for the variables SGR andsurvival rate, using the results of eight experimentsin such polycultures at the Co Do rice^¢sh experimentalstation. The SGR of C. carpio declined with increasingrice density. Interspeci¢c competition withO. niloticus also had a negative e¡ect on C. carpioSGR.When fertilizer ormanure is added to the trenchof the rice^¢sh ¢eld or when extra food can be givento the ¢sh, O. niloticus seems more appropriate thanC. carpio. The survival rate of C. carpio depended onseason, C. carpio stocking weight and density andthe biomass of wild ¢sh species.To obtain higher survivalrates, one should stock fewer ¢sh but of a largersize, after thorough eradication of wild ¢sh species.
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