A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand

Thesis (M.Eng.) - Asian Institute of Technology, 1978

Tilapia is a famous tropical fish which may be cultured in vegetable irrigation ditches to use the waste matter for food. Routine agricultural chemical activities on those vegetable farms for pest control have shown distinct effects on Tilapia production. Azodrin (organophosphate pesticide) sprayed in one vegetable farm studied in this thesis led to high azodrin residue accumulations of 1.011 ppm and 0.837 ppm for Tilapia mossambica and Tilapia nilotica, respectively. The rapid decomposition of azodrin within three weeks after spraying, however, may give the users such confidence that azodrin has advantages both for agriculture and fisheries if a vegetable and fish harvest can be made at the same time. Chlorinated hydrocarbon pesticides were examined, but very low concentration were present which apparently did not do any damage on fish. Perhaps the cool and rainy season from September to December in Thailand greatly lowers the toxicity of pesticides on fish. "Mono-sex" culture of male Tilapia production in 3.5 months reached 3269 kg/ha and 2808 kg/ha for T.nilotica and T.mossambica, respectively where the above chemicals were sampled.