A PRELIMINARY STUDY ON HETEROTROPHIC BACTERIA IN HIGH-YIELDING FISH POND

Aerobic heterotrophic bacteria were identified and counted monthlyfrom March to October in pond water and sediment of a high-yielding polyculturedfish pond. During the experiment, ranges of total bacterial count (TBC) and he-terotrophic bacterial count (HBC) in pond water were 1.30-15.90×10⁵ cells/mland 1.56-14.50×10⁴ cells/ml respectively. while TBC and HBC of pond sediments were 1.20-68.0×10⁶ cells/g and 1.94-19.90×10⁵ cells/g respectively. Data ana-lysis showed that fluctuations of the bacterial load of pond were correlated withseveral environmental factors. 11 genera of heterotrophic bacteria were found inpond water, of which the nitrogen-fixing bacteria (e.g.Azomonas) were domina-ting. 8 genera of heterotrophic bacteria were found in pond sediment, of whichgram positive bacteria (e. g. Bacillus) were dominating, Pseudomonas commonlyoccurred in pond water and sediments. Results of the experiment indicated that thechanges of bacterial load in high-yielding polycultured fish pond revealed certainregularity and the fish yield had a bearing upon the composition of the bacterialcommunity in the pond.