Abstract: Background Opsariichthys bidens is an economic fish species with great potential for development in freshwater aquaculture in China, with delicious meat and strong adaptability, but the efficiency of artificial breeding is limited by the level of ovarian development of the parent fish.ObjectiveIn order to investigate the effect of culture density on the ovarian development of parental O. bidens.Methods Parental O. bidens of the same specification and healthy physique were selected and randomly divided into four density gradients: a low density group (M₁, 2 kg/m³), a medium density group (M₂, 4 kg/m³), and two high density groups (M₃, 6 kg/m³), and (M₄, 8 kg/m³) for cultivation, and the experimental cycle was 45 d. The ovarian Sections of ovaries were observed and counted to calculate the gonadal index and the proportion of phases of ovarian development to stage IV; the contents of conventional nutrient fractions such as moisture, crude protein, crude fat, crude ash, phosphorus and calcium of the ovaries were determined; and statistics on the catalysis rate, hatching rate and fertilization rate were made. Results The results showed that the gonadal indexes of the medium density group (13.35%±1.97%) were significantly higher than those of the other density groups (P<0.05); and the phase-to-phase ratio of oocytes entering stage IV in the medium density group was 46.62%±3.20%, which was significantly different from that of the other groups (P<0.05); Regarding the conventional nutrient composition of the ovaries, the moisture content of the ovaries of the O. bidens in the medium density group was significantly lower (P<0.05) and the crude lipid content was significantly higher (P<0.05), while the differences in the contents of crude protein, ash, calcium, and phosphorus were not significant (P>0.05); In terms of fecundity, the medium density group had significantly (P<0.05) higher fecundity (93.30%±3.30%) and hatchability (81.40%±4.00%) than the other density groups and had the optimum fertilization rate. Conclusion The above results indicate that reasonable culture density can improve the level of ovarian development of parental O. bidens to a certain extent.