2.1 Sample collection
A wild female C. undulatus(Fig. 1), caught in Guangzhou, Guangdong province, China, was used for genome sequencing and assembly. The fish was determined to be 4 years old, based on annuli otolith interpretation. The living fish was transported to the laboratory. The brain, muscle, liver, spleen, olfactory organ, gonad, and retina tissues of the fish were collected, quickly rinsed with 1× phosphate buffered saline (PBS) solution, and then frozen in liquid nitrogen for 24 h. All samples were stored at −80 °C before sample preparation.