Assessment of fatty acid composition and effect of temperature and salinity on embryogenesis of pangasius nasutus

Abstract

Pangasius nasutus, a well-known freshwater fish recognized for its economic importance in the Pahang river, Malaysia, is traditionally sourced from the wild. However, this reliance on wild catch poses a threat to natural resources. Implementing artificial breeding techniques for P. nasutus offers benefits such as increased output of P. nasutus and significantly improved survival rates. This study aimed to characterize important parameters and characteristics in the artificial breeding of P. nasutus. The objectives included assessing the fatty acid composition of eggs during embryogenesis, investigating the impact of temperature on hatching and survival rates, and examining the effect of low salinity on hatching and survival rates of P. nasutus in captivity. The results showed average values of fatty acid composition such as EPA (C20:5n3), DHA (C22:6n3), and ARA (C20:4n6) were 0.23, 5.98 and 6.59 respectively in the fertilised eggs of P. nasutus. While the value of the ARA/DHA ratio for all stages in the embryogenesis of P. nasutus was between 0.79-1.11. The results of the study found that there was no significant change in the composition of fatty acids in eggs during embryogenesis. In the study of the effect of temperature, fertilised eggs of P. nasutus were exposed to different temperatures of 24, 26, 28 and 30°C. The results of the study found that temperature exposure at 26°C had the highest percentage of hatching and survival which were 25.58 and 58.56%, respectively. The regression analysis revealed that the optimal temperature for hatching was 26.9 °C, while the optimal temperature for survival was 24.9 °C (P<0.05). In the study of the effects of salinity, fertilised eggs were exposed to different salinity treatments of 0, 1, 2 and 3 ppt. The results of this study showed that the salinity treatment at 1 ppt had a significantly higher hatching and survival rate (P<0.05) compared to other treatments with a percentage of hatching rate of 52.5 ± 3.7% and survival of 72.0 ± 5.0%. However, the regression analysis exerted the optimal salinity for hatching and survival were 0.71 and 0.77 ppt, respectively. In conclusion, this study was able to assess the fat composition of eggs in all stages of embryogenesis, as well as determine the optimal temperature and salinity for hatching and survival of P. nasutus eggs. These are important parameters in the embryogenesis of P. nasutus, contributing to the knowledge of artificial breeding in P. nasutus.