碩士 / 國立臺灣海洋大學 / 水產養殖學系 / 105 / This study aimed to delve into the histology and infectious disease investigation of freshwater stingrays of the genus Potamotrygon cultrured in Taiwan. On the basis of the results of the disease investigation, methods for control of cultured freshwater stingray disease had been studied, and, in the end, making some suggestion for farmers to control the diseases.
Histological observation revealed that the liver of freshwater stingray contained abundant of fat. This stingray presented a classical architecture of hepatic lobules, as in mammals, with portal triad, central veins, but the borders were not clear. There were red pulp and white pulp in the spleen but it lacked obvious germinal center. The kidney was made up of glomerulus and tubules, and two types of tubules were observed. The pancreas presented white to flesh color and there were tubules in it. The digestive tract of freshwater stingray could be divided into esophagus, cardiac stomach, pyloric stomach, duodenum, and spiral valve. The other organs in the abdomen cavity resembled to that of bony fishes.
According to our study, cultured freshwater stingrays in Taiwan are easily infected by Trichodina sp., Potamotrygonocotyle sp., Tetrahymena sp., and intestinal ciliates. The results of bacterial isolation showed that the bacteria isolated from freshwater stingrays with severe sepsis were mainly composed of Aeromonas hydrophila and Citrobacter freundii. Mixed infections of the two bacterial species and the parasites are common.
In order to control common pathogens of cultured freshwater stingray, disinfectant experiments were performed using chlorine dioxide. Using 0.4 ppm chlorine dioxide disinfected cultured water had a killing rate of 52.9% in an hour. Using 4 ppm chlorine dioxide to disinfect blood worms, frozen white shrimp and frozen loach for 30 minutes, no effect on palatability was found with best killing rate of 50.2% on blood worms.
According to the results, it is suggested that stingray farmers should perform quarantine, food disinfected and environment control regularly to reduce disease risk.
| Identifer | oai:union.ndltd.org:TW/105NTOU5086004 |
| Date | January 2017 |
| Creators | Su, Keng-Yi, 蘇耿誼 |
| Contributors | Lee, Kuo-Kau, Liu, Ping-Chung, 李國誥, 劉秉忠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 84 |
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