EST,ADH,LDH,SDH,POD,SOD,CAT,G-6-PD and COX isoenzymes in eight tissues (i.e.brain,skin,muscle,liver,pancreas,gill,eye lens and heart) of Symphysodon spp.were studied by PAGE.And the locus and electrophoretogram in every tissue were analyzed.Total 29 gene loci were detected with corresponding alleles.All the 9 isoenzyme systems in every tissue have distinct and stable electrophoretograms.Besides CAT,the electrophoretograms of the other isoenzymes varied from different tissues or individuals.The isoenzymes and their activity were consistent with physiological functions.The liver and pancrease were abundant with locus.The EST and ADH in the liver have high activities.There existed Cloci in the LDH of livers and eyes,and the C-loci of the eye lens were heterozygous with the A-loci and Bloci.