Why is cannibalism less frequent when larvae of sutchi catfish Pangasianodon hypophthalmus are reared under dim light?
Survival rates of the larvae of sutchi catfish Pangasianodon hypophthalmus are reported to be three times higher under dim conditions (0.1 lx) than those under 100 lx. In this study, larval behaviour of sutchi catfish was examined under various light intensities (<0.01, 0.1, 1, 10 and 100 lx...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English English |
| Published: |
Wiley-Blackwell
2015
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/45466/ http://irep.iium.edu.my/45466/ http://irep.iium.edu.my/45466/ http://irep.iium.edu.my/45466/1/2015_aquacultue_research.pdf http://irep.iium.edu.my/45466/4/45466-_wos_and_scopus.pdf |
| Summary: | Survival rates of the larvae of sutchi catfish Pangasianodon
hypophthalmus are reported to be three
times higher under dim conditions (0.1 lx) than
those under 100 lx. In this study, larval behaviour
of sutchi catfish was examined under various light
intensities (<0.01, 0.1, 1, 10 and 100 lx) using a
CCD camera to understand why survival rates
vary under different light intensities. Five-day-old
larvae showed significantly higher swimming
activity under <0.01, 0.1 and 1 lx than those
under 10 and 100 lx. On the other hand, the
larvae showed significantly higher aggressive
behaviour under 10 and 100 lx; swimming larvae
attacked resting individuals more frequently under
10 and 100 lx than those under 0 and 0.1 lx.
Aggressive behaviour was considered to induce
lesions, inflicted by the sharp teeth of attacking
larvae, on larval skin surfaces. It is considered that
the chemical substances would generate from
injured skin surfaces then acted as stimuli, causing
the cannibalistic behaviour in other fish around
the injured fish. This study provided evidence that
the observed higher survival rates depended on
lower frequency of aggressive behaviour under
dark or dim conditions. It is therefore recommended
that larval rearing of sutchi catfish be
conducted under dim (less than 1 lx) conditions. |
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