ABSTRACT
Total aerobic plate counts for bacterial colonies in the Bullacta exarata ranged from 7. 3?10 5 to 2. 8?10 6 cells per gram. 217 strains of bacteria were isolated from the Bullacta exarata and 88. 5% of them were Gram-negative rod . The predominant genera were composed of Enterobacteriaceae (61 strains), Aeromonas (58), Vibrio (27), Pseudomonas (21). The results indicate that total bacteria numbers exceeds state standard by 1～2 quantity level in every samples. The coliform bacteria numbers exceeds health standard in sample of seven and nine month. It should be brought to attention. The microflora were composed of ten genus , predominant Bacillus of rearing shoal were few in the Bullacta exarata that may play a special role for regulating and controlling the microbial community .