Hematology of Pangasionodon hypopthalmus Reared Under Controlled Photoperiod

Abstract

Manipulated photoperiod has been used to improve the growth of cultured Pangasionodon hypopthalmus. Photoperiod length affects the fish physiology in general and thus reflected in its hematological condition. The hematology of P. hypopthalmus reared in short photoperiod was studied in May–August 2020. There were three treatments applied, namely natural photoperiod (P-Nat, fish tanks were placed under clear plastic tent), 18 hours dark (P-18D, the tanks were placed under dark tarp tent for 18 hours) and 24 hours dark (P-24D, the tanks were placed under dark tarp tent continuously). The fish (3 inches TL, 4 grams BW) were reared in circular tanks ( 100 L) at a density of 30 fishes/tank and fed with commercial fish feed pellets twice a day,, ad libitum. Blood samples were obtained prior to the experiment and at the 8th week. Results showed no significant differences in hematological parameters of the fishes among treatments. The number of erythrocytes and leucocytes in the pre-treated fish was approximately 1,850,000 and 55,200 cells/ml, respectively. While those of the treated fish was 1,760,000 and 54,600 cells/ml (P-Nat); 1.760.000 and 55,000 cells/ml (P-18D) and 1,790,000 and 55,000 cells/ml (P-24D). In pre-treated fish as well as all treated fishes, hemoglobin was around 10 g/dL and glucose was around 110 mg/dL. The percentage of leucocyte type cells were as follows: lymphocyte 65%, monocyte 24%, thrombocyte 6%, neutrophil 3%, eosinophil 1% and basophile 1%. The value of hematological parameters indicate that the fish was in normal and healthy condition and thus it is proved that shortened photoperiod do not affects P. hypopthalmus health in general.