Recycling wastewater from intensive hybrid catfish (Clarias Macrocepharus x Clarias gariepinus) culture for semi-intensive Nile tilapia (Orechromis niloticus) culture in cement tanks | |
| Author | Ruechuta Sethteethunyahan |
| Call Number | AIT Thesis no. AS-98-13 |
| Subject(s) | Nile tilapia Fish-culture Fish-culture--Water-supply--Recycling |
| Note | A thesis submitted in partial fulfillment of the requirement for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | An experiment was conducted for 90 days at the Asian Institute of Technology in Thailand, to determine the optimal frequency of water recirculation and to maximize the nutrient utilization efficiency in a catfish-tilapia integrated recycling culture system. Hybrid catfish (Clarias Macrocepharus x Clarias gariepinus) (8-9 g size) and sex-reversed all-male Nile tilapia (Oreochromis niloticus) (6-8 g size) fingerings were stocked in 12 paired concrete tanks (2.5 x 2 x 0.9 m) at a densities of 27 and 3 fish/m2 " respectively. Three closed tanks were used for catfish culture only as the control. The water between the paired catfish and tilapia tanks was recirculated once every three days or seven days, to determine the effects of water recirculation frequency on growth performance of both catfish and tilapia, water quality and nutrient utilization efficiency. Catfish was fed with commercial floating pelleted feed (30% crude protein) twice daily at 3-5% body weight per day. Water quality was monitored biweekly for chemical parameters and weekly for physical parameters. There were no significant (p > 0.05) difference in survival, net and gross yield of hybrid catfish among treatments. However, water recirculation increased daily weight gain of individual catfish significantly (p < 0.05). The survival and net fish yield of hybrid catfish ranged from 90.37% to 98.52% and from 2.66 to 2.97 kg/m2 , respectively, in all treatments. Water recirculation in the 3-day inte1val treatment caused mass m01tality of Nile tilapia in two of three replications. The net tilapia yield in the 7-day interval treatment ranged from 0.12- 0.19 kg/m2 , which was significantly (p < 0.05) higher than that in the 3-day inte1val treatment. Producing 1 kg of live catfish generated about 41 g nitrogen (N) and 8.8 g phosphorus (P) as metabolic wastes. Approximately 62% of the total N input and 55% of total P input from the feed were released to the tanks. From the released nutrients. 0.68-1.94% of total N and 0.86- 2.48% of total P were recovered by tilapia; 10.06-16.43% of total N and 5.13-11.60% of total P accumulated in the tank sediment; 30.14-41.52% of total N and 22.68-35.62% of total P remained in the water column, and 10.46-14.29% of total N and 14.26-19.55% of total P were unaccounted for. The present experiment demonstrated that Nile tilapia can be cultured in an integrated recycling system to extract some nutrients, which might be released into the environment, and suggested that the catfish:tilapia ratio can be lower to allow Nile tilapia to reuse more nutrients contained in catfish wastes and thus to enhance the nutrient utilization efficiency in the catfish-tilapia integrated recycling culture system. |
| Year | 1998 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Lin, C. Kwei ;Yi, Yang; |
| Examination Committee(s) | Demaine, Harvey ;Mair, Graham C.; |
| Scholarship Donor(s) | Danida; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1998 |