Stocking ratios of hybrid catfish (Clarias macrocephalus x C. Gariepinus) and Nile tilapia (Oreochromis niloticus) in an intensive polyculture | |
| Author | Nguyen Thanh Long |
| Call Number | AIT Thesis no.AQ-03-24 |
| Subject(s) | Nile tilapia Catfishes |
| Note | A thesis submitted partial fulfillment of the requirements for the degree of Master of Science, School of Environmnet, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AQ-03-24 |
| Abstract | An experiment on intensive polyculture of hybrid catfish and Nile tilapia was conducted in fifteen 5-m2 outdoor cement tanks at the Asian Institute of Technology for 91 days, to determine the appropriate stocking ratio of Nile tilapia ( Oreochromis niloticus) to hybrid catfish (Clarias macrocephalus x C. gariepinus) and effects of different stocking ratios on the growth of both Nile tilapia and hybrid catfish, water quality, nutrient utilization efficiency and economic returns. There were seven stocking ratios (treatments) of Nile tilapia to hybrid catfish. Hybrid catfish fingerlings of 25-26 g size were stocked at 100 fish per tank (20 fish/m2 ), while Nile tilapia fingerlings of 20-23 g size were stocked at 0, 5, 10, 15, 20, 25 and 30 fish per tank (0, 1, 2, 3, 4, 5 and 6 fish/m2 ), giving stocking ratios of Nile tilapia to hybrid catfish as 0:100, 5:100, 10:100, 15:100, 20:100, 25:100, and 30: 100, respectively. The control (0: 100) had three replicates, while other treatments had two replicates each. No fertilizers were applied to the tanks. Floating pelleted feed (30% crude protein) was given twice daily at 0830 and 1530 h 6 days per week. Feed rations were calculated based only on hybrid catfish biomass estimated by biweekly fish sampling and observed survival rate. Feeding rates of 5% and 3% body weigh per day were used for hybrid catfish smaller than 100 g and larger than 100 g, respectively. All tanks were aerated by airstones throughout the experimental period. The addition of Nile tilapia into hybrid catfish tanks did not cause any significant effects on survival, growth and yields of hybrid catfish (P > 0.05). Survival of Nile tilapia was not significantly different in the polyculture treatments (P > 0.05). With increasing stocking ratios of Nile tilapia to hybrid catfish, mean tilapia weights at harvest decreased linearly, while both net and gross tilapia yields increased linearly (P < 0.01). FCRs based on either hybrid catfish alone or combined hybrid catfish and Nile tilapia were not significantly different among all treatments (P > 0.05). Combined net yields were not significantly different among all treatments (P > 0.05), however, combined gross yields increased linearly with increasing stocking ratios of Nile tilapia to hybrid catfish (P < 0.05). To produce 1 kg of live hybrid catfish and Nile tilapia generated 18-22 g nitrogen (N) and 3 g phosphorus (P) as metabolic waste. Approximately 34-40 % of total nitrogen and 52- 55% of total phosphorus input from the feed were released in the tanks. There were no significant differences in nitrogen utilization efficiency among the catfish monoculture and polyculture of hybrid catfish and Nile tilapia (P > 0.05), however, phosphorus utilization efficiency was significantly lower in the monoculture than in the polyculture (P < 0.05). The addition of Nile tilapia into hybrid tanks did not improve water quality. Water quality fluctuated largely among experimental tanks and deteriorated towards the end of the culture period in all treatments. Compared to hybrid catfish monoculture, the ratio of added return to added cost was highest in the polyculture at 10: 100 ratio of Nile tilapia to hybrid catfish, intermediate at 5: 100 ratio, and lowest at higher ratios (15-30: 100). This study has demonstrated that the intensive polyculture of hybrid catfish with Nile tilapia is feasible and that the appropriate ratios of Nile tilapia to hybrid catfish are 5-10: 100. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AQ-03-24 |
| 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 | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Yi, Yang; |
| Examination Committee(s) | Bart, Amrit ;Yakupitiyage, Amararatne ;Lin, C.Kwei; |
| Scholarship Donor(s) | Cantho University/CRSP; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2003 |