Distribution of nitrifying bacteria in fish culture tanks: influence of management factors.

ABSTRACT

Examination of microbial populations of ammonia and nitrite oxidizers in model tanks used for farming of air-breathing catfish (ABFFS), polyculture of herbivorous carps (PS) and control system (CS) revealed maximum abundance of ammonia and nitrite oxidizers in ABFFS and minimal in CS. In any of the two culture systems, the chemical concentration or density of bacteria developed due to feed application was many times higher than other management factors. At a given time, the bacteria of each group occurring in any management protocol of ABFFS was about 10% higher than PS. Culture of air-breathing fishes caused greater abundance of ammonia and nitrite oxidizers than the herbivorous carps. There was a strong positive correlation between each of the chemical concentration of produced nitrite (ammonia oxidizers) and density of nitrite oxidizers and ratio of total nitrogen to phosphate.