The optimal light conditions for the survival and growth performance, and the visual adaptations in larval and juvenile Sutchi catfish Pangasianodon hypophthalmus /
Sutchi catfish Pangasianodon hypophthalmus is one of the major cultured freshwater fish in the aquaculture industry. Low larval survival rates due to strong cannibalism have affected the efficiency of the seed production. Optimal rearing conditions during early larval and juvenile rearing are vital...
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuantan, Pahang :
Kulliyyah of Science, International Islamic University Malaysia,
2018
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | Sutchi catfish Pangasianodon hypophthalmus is one of the major cultured freshwater fish in the aquaculture industry. Low larval survival rates due to strong cannibalism have affected the efficiency of the seed production. Optimal rearing conditions during early larval and juvenile rearing are vital to produce sufficient quantity and high quality seed fish. Hence, this study aimed to investigate, through a multidisciplinary experimental approach, the appropriate light conditions for improvement of survival and growth performance in the rearing of sutchi catfish larvae and juveniles. Fish rearing experiments (Experiment 1) under different light wavelengths (represented by colour of light; white, blue, green, yellow and red lights) and intensities (1.40×10-3, 1.40×10-2, 1.40×10-1 and 1.40 µmol/m²/s) revealed that both light wavelength and light intensity are equally important for the survival and growth performance of sutchi catfish larvae and juveniles. Whole-body cortisol concentration assay (Experiment 1) was carried out to evaluate growth performance of the larvae and juveniles physiologically. The results of simple main effects analysis showed that whole-body cortisol concentration of the larvae and juveniles can be significantly affected by light wavelength and intensity. Relative eye size and retinal histological examinations (Experiment 2) showed that sutchi catfish was sensitive to light environment as it displayed characteristics of a visual feeder. Sutchi catfish possessed relatively large size of eyes with maximum density of cone photoreceptor cells similar to that found in visual feeder fish species. Lastly, spectrophotometry method (Experiment 3) was employed to examine the spectral absorbance of wholemounts of retina to understand the visual sensitivity of sutchi catfish. Spectral absorbance curves obtained from the spectrophotometric measurements clearly suggested that sutchi catfish has visual spectral sensitivity adapted to red light with the presence of red-sensitive visual pigments in the retina. In conclusion, the present study confirmed the necessity of appropriate lighting conditions favourable to sutchi catfish larvae and juveniles with the knowledge on the retinal adaptations and visual spectral sensitivity. Based on the present results, longer light wavelengths with lower light intensities are suggested for the rearing of sutchi catfish larvae and juveniles in aquaculture systems for the efficiency of seed production. |
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| Physical Description: | xxi, 176 leaves : colour illustrations ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 123-152). |