Effects of size-sorting on subsequent growth and cannibalism in hybrid catfish fry/fingerlings | |
| Author | Ma, Li |
| Call Number | AIT Thesis no. AE-92-25 |
| Subject(s) | Fish-culture Catfishes |
| Note | A thesis submitted in partia1 fu1fi1lment of requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | A two-factor experiment was conducted to investigate the effects of stocking density on growth, survival, and size distribution of hybrid catfish fry (female Clarias macrocephalus X male C. gariepinus). The fry stocked at lower densities showed better growth performance and survival but with greatest coefficient of variance (CV) in size distribution. Fry fed with high food ration achieved better growth performance but medium food treatment reduced growth differential. Survival rate of fry fed with medium food ration was higher than that fed with low food ration but not significantly different from treatment of high food ration (P<0 . 05) . The final weights of fry ranged from 46 . 4 to 121.1 mg, and survival rates from 53.3 to 83.1%. Over the 21-day period the largest size variation with highest CV was found in the fry raised at intermediate density of 15 fry/L and fed with low food _ ration that was related to a highest cannibalism. The fry raised at 20 fry/L and fed with medium food ration showed better growth, size distribution and survival. Experiment 2 investigated the effects of size-grading on growth and survival in growout system. Fingerlings of average weight 4 .1 g were divided into four size groups consisting of large, medium, small and ungraded fish, each size group was stocked in 3 replicate cages. The average final weight ranged from 44.5 g (small fish) to 95.8 g (large fish) and survival was higher than 97.5% over 45 days. The rearing of hybrid catfish in size-graded groups did not result in significant increase in biomass gain compared to that obtained in mixed-size groups. High levels of interactions between fish of similar size may be a major factor affecting the growth and size depensation in size-sorted large and medium fish groups. The two experiments revealed that growth depensation was determined mainly by heritability combined with culture conditions and social interactions. |
| Year | 1992 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Lin, Chang Kwei |
| Examination Committee(s) | Phillips, Michael J. ;Yakupitiyage, Amararatne |
| Scholarship Donor(s) | Japan; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1992 |