黑料网

Abstract

Tests were done to measure the efficiency of formalin solution in diminishing the peritrichous ciliates on the surface of cultured mud crab. The tests were done at concentrations above and below those being used in mud crab culture and were schemed to state the concentration giving the most effective rapid reduction of ciliates. The larvae from mud crab ( Scylla serrata ) were divided equally (after the diagnosis of significant ciliate epifaunation) into 500ml of glass bottles each with 10 mud crab larvae. These bottles were divided in six treatments of different concentration of formalin: 20, 40, 60, 80, 100 and 120 ppm; three replicates per treatment. The treatments were conducted under static conditions for 48 hours. Ciliate levels were measured on every six hours till forty eight hours. In all treatments ciliates only shrink but didnot die and the larvae in control survived for 48 hours whereas the larvae treated with formalin started to die and become inactive after exposure. Therefore, under static conditions formalin is not efficient enough to kill these type of ciliates.

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