Ahmed, Saleh creator Lin, Chang Kwei Chairperson Little, David C. Examination Committee Kamtorn Kaewpaitoon Examination committee Government of Bangladesh / Asian Development Bank (ADB) Scholarship donor text th Bangkok Asian Institute of Technology 1995 monographic eng

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116 leaves + 1 online resource Chlorin e is a low-cost and effective disinfectant in fish ponds where predatory fish are potential enemy of stocked fry. A series of short-term acute chlorine toxicity tests to tilapia ( Oreochromis niloticus) and rohu fry ( Labeo rohita) were carried out in clear water under laboratory conditions. The LC100 for 6, 12 and 24 hrs for both tilapia and rohu were at 7.89 and 7.12 ppm, respectively. For both fishes the mortality rate did not increase after 6 hrs of contact time. Temperature and pH changes up to 6 hrs exposure time accelerated the toxicity levels. An additional test on rohu with urea added water found lower toxicity of chlorine with urea. A lethal toxicity test of chlorine on snakehead (Channa strait us), catfish ( Clarias macrocephalus x C. ga.riepinus) and climbing perch (Anabas testudineus) were conducted in communal concrete tanks with green water. The 1003 mortality of those 3 fish species occurred after 6 hrs of exposure time in SO ppm chlorine treatment. The calculated 24-hr LC100 were 51.68, 51.06 and 50.83 ppm for catfish, snakehead and climbing perch, respectively and those values were almost equal to LC100 for 6 hrs and 12 hrs. Thus, 6-hr contact time appeared to be most suitable time interval to calculate LC100 of chlorine to the fishes. Chlorination severely affected the zooplankton population and net primary productivity of phytoplankton in water that received test. A short-term residual toxicity to tilapia fry tested in tanks where chlorine were applied to kill predators fish showed that fry would be stocked in the tanks 5 days after chlorine treatment, but it is recommended to stock after 7 days of chlorination when plankton community is reestablished. A long-term residual toxicity test was conducted for 2 months to detect the potential persistent chlorinated compounds in the same environment. Results showed that there was no effect of residual chlorine on survival, growth and production of fish tested, the nile tilapia. Water quality parameters were within acceptable limits and no significant differences observed between control and treatments. The study revealed that chlorine can be effectively used as piscicide without adversely affecting the fish growth , production and water quality. A thesis presented in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources, and Development Thesis (M.Sc.) - Asian Institute of Technology, 1995 Fish-culture Fish ponds Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B15215 http://203.159.5.9/ait-thesis/detail.php?q=B15215 130598 20260817163523.0