Biological aspects of Pangasius hypopthalmus reared under controlled photoperiod

Abstract

A study aims to understand the effects of photoperiod manipulation on the biological aspects of Pangasius hypopthalmus was conducted in June 2019. There were 3 treatments applied, namely control (natural light); 24 hours dark (24D) and 18 hours dark (18D). The treated fishes were reared in tarp ponds (75 - 50 - 60 cm) and kept under dark blue plastic tents 24 hours (24D) and 18 hours (18D) continuously. There were 20 fishes/tank and they were fed on commercial fish feed 2 times/day, 5% of total fish body weight. Data on fish growth were collected 3 times, just before the treatment, in the 2nd and 4th weeks after the photoperiod treatment. Data on the fish behavior were collected during the 2nd week, by monitoring fish behavior hourly for 72 hours continuously. Data on blood condition were collected from the fish 2 times, before the treatment and in the 4th week. Results indicates that the 24D provided the best results in fish growth, by the 4th week, the fish TL value was 123.5 mm and BW was 5.6 gr. The blood condition of fish in all treatments were normal and there was not significantly difference, with hematocrit value was 30%, 1.5% of leucocrite levels, 70% of lymphocyte and 30% of other leucocyte types. The shortened photoperiod duration positively affects the growth of P. hypopthalmus growth, but it does not affect the biological aspect of the fish in general.