The occurrence of epitheliocystis in Nile tilapia (Oreochromis niloticus) nurseries | |
| Author | Phan Thi Van |
| Call Number | AIT Thesis no. AS-98-11 |
| Subject(s) | Nile tilapia Fish-culture |
| Note | A thesis submitted in 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-98-11 |
| Abstract | The Nile tilapia (Oreochromis niloticus), a member of family Cichlidae, has become one of the most commonly cultured species, especially in tropical and sub-tropical countries. Although tilapia is known to be tolerant to poor water quality and relatively low in apparent disease occurrence, the fry mortality in nurseries has been high. Epitheliocystis, a disease known to occur commonly in marine fish, bivalves and crustaceans, has also been identified to infected tilapia. However, few investigations on epitheliocystis in tilapia have been conducted. The present study examined a total of 780 Nile tilapia (Oreochromis niloticus) fry from 5 batches for epitheliocystis during sex reversed period at AIT's nursing ponds. Histological study revealed that fish from all five batches were highly (70-100%) infected by epitheliocystis. A round-to-oval shape, granular basophilic, gram negative cysts, ranging from 32- 56x40-60 µm were found in gill epithelial cells of tilapia fry. The fry mortality reached 59% and 66% when they were held at high stocking density (3,000 fish/m2). Electron microphotographs of infected cells revealed that the pathogen had two morphological forms: elongated cells and small cells with the size at 1-2.5x0.3-0.4µm and 0.57-0.7x0.3-0.4µm respectively. The pathogen in tilapia was Clamydia-like organism belonging to the order of Clamydiales as earlier described from epitheliocystis infections in many other species. The infection occurred even when the water quality was within the suitable range for tilapia growth. The transmission of this disease can be both vertical (from broodstock to fry) and horizontal (from fry to fry). Effective preventive methods are yet to be developed. |
| Year | 1998 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AS-98-11 |
| 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) | Lin, Chang Kwei;Supranee Chinabut; |
| Examination Committee(s) | Edwards, Peter; |
| Scholarship Donor(s) | DANIDA; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1998 |