Temperature changes influenced the growth performance and physiological functions of Thai pangas Pangasianodon hypophthalmus

Abstract

Temperature is an important environmental factor that plays significant role in the growth and metabolism of fish. Hence an experiment was conducted to know the effects of temperature changes on growth, blood glucose and hemoglobin levels in Thai pangas, Pangasianodon hypophthalmus after acclimatized to four temperature conditions, such as 24 °C, 28 °C, 32 °C and 36 °C for 28 days. In addition, erythrocytic cellular abnormalities (ECA) and erythrocytic nuclear abnormalities (ENA) tests were assayed using peripheral erythrocytes after exposed to four temperature conditions. Fish were sacrificed at day -7, -14 and -28. Growth performance viz., weight gain, specific growth rate (SGR) and feed conversion ratio (FCR) were much better in 28 °C and 32 °C compared to 24 °C and 36 °C. At day-7, blood glucose levels were significantly increased in 36 °C, while at day-28 showed opposite scenario. On the other hand, at day-7, hemoglobin levels were significantly decreased in 36 °C. Interestingly, the frequencies of ECA and ENA were significantly elevated in highest temperature (36 °C) throughout the experimental period. Dissolved oxygen decreased and free CO2 increased significantly with increasing temperature, while the pH and total alkalinity showed no distinct changes throughout the study period. This study confirmed that Thai pangas feel better adaptation at 28 °C and 32 °C, while high temperature 36 °C is likely stressful and low temperature 24 °C is not suitable for growth performance to this fish species.