Chemical control of fish fry predators a toxicological study
2000
Abdi, S.Z.A. | Ayub, M. | Shah, A.A. | Mehmood, S. | Wahid, I. | Mir, S.S. | Arshad, M. | Mushtaq, M. (Fisheries Research and Training Inst., Lahore (Pakistan))
Fry rearing is the key step in successful fish farming. During fry rearing the problem of predation by the aquatic insects, which are produced during the preparation of nursery ponds is one of the main impediments in the way of optimum survival rate of fish fry (Burleigh et al., 1993). In practice, these predators are controlled by the use of different chemicals. Present studies are done using various organophosphates with trade name as Systoate, Malathion, Hostathion, Sumithion, Alfachron, DDVP, Thunder and Nuvon to determine the dose most affective for predation control and the safest for fish fry. Lc50 was determined for each chemical and then the safest doses for fish fry were also determined as 0.2mg/1 (Nuvon), 0.5mg/1 (Thunder), 0.02mg/1 (Sumithion), 0.5mg/1 (Systoate), 0.25mg / l (Hostathion), .2mg/1 (Alfachron), 0.8mg/1 DDVP and 0.08mg/1 (Malathion). The studies further investigated the residual effects of these chemicals. The results showed that the selected doses of these chemicals are cleared in fish and water within 16-36 hours of treatment without any residual effects. The study proved that these chemicals can be used in selected doses for the control of fish fry predation without any harmful effects on fry (Short term), (Schmuck et al., 1994) and on flesh quality (Long term), (Sharma et al., 1995).
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