In LKB electrophoresis set with 4.4% polycrylamide gel, the lactate dehydrogenase(LDH) and malate dehydrogenase (MDH) were examined from 11 tissues-white muscle, eye lens,brain, liver, kidney, gonad, heart, spleen, fin, red cell and serum of blunt snout bream. Qualitativeand quantitative analysis on mobility and activity were conducted by a LKB Ultorscan laser de-nsitometer. The activity and mobility of isozymes in different tissues showed a significant tissuespecificity.