Abstract: Siniperca chuatsi serum Ig was purified by affinity chromatography for prepared polyclonal antibody against Siniperca chuatsi serum Ig.Twenty-five fish's sera were collected and purified the serum Ig by euglobulin precipitation.Serum Ig could react with polyclonal antibody that against Siniperca chuatsi serum Ig were screened.The polyclonal antibody could recognize Siniperca chuatsi,Micropterus salmoides,Trachinotus ovatus,Oreochromis niloticus,Lateolabarax japonicus,Oreochromis sp., Epinephelus awoara,Pseudosciaena crocea, Sebastiscus marmoratus, Sciaenops ocellatus, Sparus macrocephalus, Scophthatmus maximus, Paralichthys olivaceus, Sebastiscus marmoratus, serum Ig heavy chain and light chain.The polyclonal antibody reacted with many protein bands from purified serum of five species Cypriniformes, four species fish of Siluriformes, purified serum of Anguilla anguilla and Muraenesox cinereus.Oreochromis niloticus were immunized intraperitoneally with aeromonas hydrophilla ZN1 outer membrane proteins immune stimulating complexes(ISCOM).The antibody in the serum was detected by ELISA, the polyclonal antibody against Siniperca chuatsi from rabbit was used as second antibody.The result showed that the antibody from immunized group was higher than that from control group.