Quantitative assessment of bacterial flora during a production cycle in commercial farm raised tilapia

Abstract

Study of bacterial flora is one of the important aspects of assessing the pond dynamics
and fish health in farming systems. The present study determined bacterial load in pond water,
sediment and gill of farmed tilapia (Oreochromis niloticus) throughout a 60 days production
cycle in a private farm of Trishal, Mymensingh. Around 30 g sized tilapia fingerlings were
stocked in three ponds at a stocking density of 6,1000 fingerling/ha. Sampling for bacteriology
and water quality was done every 15 days intervals. No particular trend was observed in
bacterial load in either pond water, sediment or gill of fish throughout the study. Highest
bacterial load in pond water was 5.83±4.48×106cfu/ml found at day 30. In the pond sediment,
bacterial load was 3.50±0.50×107cfu/g observed at the end of the experiment on day 60. In
fish gill, average bacterial load among the ponds ranged between 1.81±2.32×107 and
2.81±3.62×107cfu/g. Water quality parameters including temperature, NO3, NO2, PO4, NH4
and DO of pond water revealed that they were within the suitable range for the freshwater fish
culture throughout the farming phase.