Keywords: 
• breeding density /
• Archocentrus nigrofasciatus var.× Mikrogeophagus ramirezi /
• growth /
• physiology /
• reproduction

Abstract: Four culture density groups (D₁:1.16 kg·m^-3;D₂:2.32 kg·m^-3;D₃:3.48 kg·m^-3;D₄:4.62 kg·m^-3) were set up to culture Archocentrus nigrofasciatus var.× Mikrogeophagus ramirezi,and the differences of growth rate,antioxidant enzyme activity and spawning quantity among different groups were compared to reveal the effects of culture density on the growth and reproduction of A.nigrofasciatus var.× M.ramirezi.The results showed that when the culture density did not exceed 2.32 kg·m^-3,A.nigrofasciatus var.× M.ramirezi was normal in mortality rate（13.06±4.59）%,number of eggs laid （133±45.00）,average initial weight of eggs （0.001 8±0.000 4） g,body mass（3.73±1.22） g,final body length （3.63±0.55） cm,specific growth rate （0.005 7±0.000 6）%,average weight gain rate （1.47±0.12）%and hatching rate （80.23±0.09）%and not high in the activities of malondialdehyde （MDA）,alanine aminotransferase （ALT）,total superoxide dismutase （SOD） and catalase （CAT）（P＜0.05）.The peak concentrations of NH₄⁺-N and NO₂^--N in aquaculture water increased significantly （P＜0.05） with the culture density.All these results show that under the condition of closed recirculating water culture,the culture of A.nigrofasciatus var.× M.ramirezi at a density higher than 2.32 kg·m^-3 will lead to an increase in peak concentrations of NH₄⁺-N and NO₂^--N and antioxidant enzyme activities,which will inhibit the healthy growth and reproduction of A.nigrofasciatus var.×M.ramirezi.The optimum breeding density of A.nigrofasciatus var.× M.ramirezi is 2.32 kg·m^-3.