Comparison of growth performance, feed utilization and morphology between homologous and heterologous juvenile Qihe crucian carp Carassius auratus

Qihe crucian carp (Carassius auratus) is a valuable fish species in China that has two reproduction modes, uni-sexual gynogenesis and sexual reproduction. However, little is known about the differences between offspring of Qihe C. auratus produced by these two reproduction modes. A thorough multi-aspects comparison of the offspring produced via the two reproduction modes would provide essential guide to aquaculturists in the artificial breeding and farming of Qihe C. auratus. Therefore, this study compared the growth performance, feed utilization, and morphological traits between homologous and heterologous juvenile Qihe C. auratus after three-month successive culture. Noticeably, homologous fish grew faster than heterologous fish in terms of the body size and final body weight; the feed intake, protein efficiency ratio, and the values of all 15 measured traits of homologous fish were significantly higher than that of heterologous fish. However, for external morphology, heterologous fish had relatively larger head size and thicker body. Additionally, the significant direct effects of the morphological traits on body weight varied between homologous and heterologous fish at different culture stages. Therefore, six independent regression equations were constructed to evaluate the relationships between different morphological traits and body weight. Further, in some traits, the homologous and heterologous fish presented discrepant allometric growth patterns. Finally, discriminant function equations (total accuracy: 92.78%) were successfully constructed based on morphological indexes to ease the identification of homologous and heterologous Qihe C. auratus. These findings suggest that homologous fish can grow faster, but heterologous fish have a thicker body, which is of higher economical value and a key parameter that determines quality and price.