在2．5m×4．0m×2．0m的水泥池中，按3．0×106尾／hm2的密度放养体长2～3cm、4～5cm和8～9 cm的凡纳滨对虾。每种规格的对虾3口池塘，其中两口池塘在对虾养殖10 d后，分别放入5尾体长为12．3～13．6 cm和17．6～18．8 cm的点带石斑鱼，另一池单独饲养凡纳滨对虾作为对照组。60 d的养殖结果显示，单养池中2～3 cm、4～5 cm 的凡纳滨对虾的质量增加显著低于混养（ P＜0.05），但存活率显著高于混养（P＜0．05）；混养时对虾规格越大增长越快，存活率越低，其中凡纳滨对虾2～3cm，点带石斑鱼17．6～18．8cm及凡纳滨对虾4～5cm，点带石班鱼17．6～18．8cm混养组合的质量增加最大（分别为7．88g与7．67g）。单养和混养时，8～9cm的凡纳滨对虾存活率差异不显著（P＞0．05）。方差分析显示，对虾规格与养殖模式间的交互作用对对虾质量增加和存活率影响极显著（ P＜0．01）；混养时对虾规格对鱼的质量增加影响不显著（ P＞0．05），17．6～18．8 cm的点带石斑鱼平均质量增加显著大于12．3～13．6 cm （ P＜0．05），对虾规格越大，混养鱼的捕食量越小，凡纳滨对虾8～9 cm ，点带石班鱼17．6～18．8 cm的混养组合对虾存活率高，鱼虾的交互作用对鱼的质量增加和捕食量均有极显著影响（P＜0．01）。凡纳滨对虾混养的利润显著大于单养（P＜0.05），其中凡纳滨对虾4～5 cm、点带石斑鱼17．6～18．8 cm ，凡纳滨对虾4～5 cm、点带石斑鱼12．3～13.6 cm ，凡纳滨对虾2～3 cm、点带石斑鱼17．6～18．8 cm混养组合的利润显著高于其他混养组合（ P＜0．05），凡纳滨对虾8～9 cm的养殖利益显著低于其他规格对虾。建议凡纳滨对虾体长达到4～5 cm开始混养点带石斑鱼。%Pacific white leg shrimp Litopenaeus vannamei with body length of 2-3 cm ,4-5 cm and 8-9 cm was reared in concrete tanks of each 2 .5 m × 4 .0 m × 2 .0 m at a stocking rate of 3000 thousand individuals/hm2 for 10 days when malabar grouper with body length of 12 .3-13 .6 cm and 17 .6-18 .8 cm was stocked into the tanks at a rate of 5 fish per tank and reared for 60 days with duplication .In the control tanks ,only Pacific white leg shrimp was stocked and cultured .The results showed that there were significantly lower body weight gain and significantly higher survival for 2-3 cm and 4-5 cm shrimps in monoculture than those in the polyculture(P<0 .05) ,the maximal body weight gain in polyculture 2 -3 cm shrimps with body length of 17 .6-18 .8 cm(7 .88 g)and 4-5 cm shrimps with body length of 17 .6-18 .8 cm (7 .67 g)groups .No significant differences in survival were found in 8 -9 cm shrimp in both monoculture and polyculture (P>0 .05) .The body weight gain and survival of shrimp were affected by the size of Pacific white leg shrimp ,culture model and their interactions (P<0 .01) .In polyculture ,there was no significant effect of the body length of shrimp on body weight gain of malabar grouper (P>0 .05) ,the body weight gain being significant higher in body length of 17 .6-18 .8 cm groups than in body length of 12 .3-13 .6 cm groups (P<0 .05) .The malabar grouper showed less predation of the larger shrimp with higher survival in 8-9 cm shrimps with body length of 17 .6-18 .8 cm malabar grouper group ,indicating that there was very significant effect of sizes of shrimp and malabar grouper on growth and predation of malabar grouper (P< 0 .01) .The benefit analysis showed that the profit of Pacific white leg shrimp polyculture was significantly higher than that in monoculture (P< 0 .05) ,the profit being significantly higher in 4-5 cm shrimps polycultured with body length of 17 .6 -18 .8 cm fish ,4 -5 cm shrimps with body length of 12 .3-13 .6 cm fish ,and 2-3 cm shrimps with body length of 17 .6-18 .8 cm fish models than in the other models .The 8 -9 cm shrimp showed significantly less profit than others ,and malabar grouper was recommended to be stocked into the tanks when Pacific white leg shrimp had body length of4-5cm.
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