Optimum dietary protein requirement of paradise fish, macropodus opercularis based on growth and reproduction performances

Abstract

The aim of this study was to assess the effects of dietary protein levels on growth and reproduction performance of paradise fish, Macropodus opercularis. A total of 540 fish (0.5±0.01 g) was offered one of six experimental diet comprising different protein levels (i.e., 25, 30, 35, 40, 45 and 50 %). Diet of 40 % crude protein produced significantly higher mean weight gain, daily growth rate, and specific growth rate and feed conversion ratio (p≤0.01). The analysis made based on the second order polynomial regression curve (R2=0.79), revealed that optimum protein levels based on fish SGR and FCR were 40 and 45 %, respectively. The average total egg production increased with increasing dietary protein levels up to 45 %. There was no significant difference in the egg diameter among groups, but egg hatchability was significantly higher (96%±2) in the fish fed diet containing 45% protein. The highest and lowest GSI was obtained in the 45 and 25% dietary protein, respectively. Fecundity was highest in the fish fed diet containing 45% (107.4±12.1) and followed by 50 (91.4±8.5) and 40 (68.5±2.6) % dietary protein. There were no significant effects of dietary protein level on egg biochemical composition and amino acid profile. The results suggest optimum dietary protein levels of 40 and 45 % for maximum growth and reproduction performance in paradise fish, respectively.