Control of ectoparasitic conditions in fry production of MT-treated tilapia (Oreochromis niloticus L.) | |
| Author | Pattareeya Sampantharat |
| Call Number | AIT Thesis no. AS-97-07 |
| Subject(s) | Nile tilapia Fishes--Breeding |
| Note | A thesis submitted in a partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AS-97-07 |
| Abstract | The infection of trichodinids affect on small fry results in severe commercial loss in intensive hatcheries producing MT-treated Nile tilapia fry. In order to control the impact of these ectoparasitic protozoans in tilapia fry production, the HACCP (Hazard Analysis and Critical Control Point)-concept, developed as a process of food quality control, was applied to control infection by trichodinids. Analysis of the fry production process and selected experiment action were conducted to establish best practices using the HACCP framework to identify Critical Control Point (CCPs) at each management step and control the problems. Observation of parasite levels on broodfish and seed harvested from commercial hapain-pond systems found treat variation with time. Only hatched seed were routinely infected with Trichodina at levels monitored between 1-272 trichodinids/fish seed. A critical control point of trichodinids infection in this stage was related to water pH level. Critical level of pH found relating to trichodinid occurrence was in acidic range. The management of pH levels using liming as a corrective action is a key management to reduce Trichodina. Water preparation and treatment in pond with spawning hapas, and seed incubation were identified further as the Critical Control Points (CCPs). The control of host organisms by application of chlorine (25 ppm) before stocking broodfish is placed to be an effective preventive measure for controlling the parasite hazard. Use of a 1 % saline solution flush for five minutes on fish seed in the hatchery both effectively reduced trichodina infection and gave the best survival of seed, trichodina levels monitored was between 15- 26 trichodinids/seed. Exchange of spawning ha pas had no effect on trichodina infection and was not a CCP. The density of hapas for sex-reversed fry significantly affected survival but water quality deterioration confounded the trial. However, at densities normal for commercial operations (10% pond area used for hapa) trichodinid occurrence on fry increased with time, suggesting preventive measures such as treatment of fry prior to stocking, rotation of ponds to reduce cross infection and allow regular sanitisation of ponds and possibly, salt flushes through the period of MT-treatment. |
| Year | 1997 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AS-97-07 |
| 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 Aquatic Systems (AS) |
| Chairperson(s) | Little, David C.; |
| Examination Committee(s) | Lin, C. Kwei ;Supranee Chinabut ; |
| Scholarship Donor(s) | DANIDA ; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1997 |