Healthy specimens ofA. testudineus(Bloch) (family: Anabantidae) weighing between 18 and 25 g and measuring between 8 and 10 cm were collected from a local freshwater pond and were acclimated for 10 days at ambient temperature (28–321C) in a concrete vat (circular vat with a diameter and a height each of 1 m, half-filled with freshwater, stored from
deep tube well) and fed with artificial diet (rice bran+wheat+oil cake) before they were used for the experiments.