COMPARATIVE STUDY ON BACTERIOLOGICAL PARAMETERS OFINDIGENOUS AND EXOTIC KOI (Anabas testudineus) AT SYLHET SADAR UPAZILA

Abstract

The present study was conducted on the bacterial population including the pathogenic bacteria in indigenous and exotic Koi (Anabas testudineus) at Sylhet Sadar Upazila during December/2014 to May/2015. For the investigation of bacterial biomass, ten (10) fish markets were selected considering the seasons winter and summer. The study concentrated on the bacteriological parameters such as Total Viable Count (TVC), Total Coliform (TC), and the prevalence of Escherichia coli, Salmonella spp. and Vibrio spp. The highest bacterial load was observed in indigenous Koi and the lowest in exotic Koi both summer and winter seasons. The highest mean bacterial load in indigenous Koi were 8.57±0.08 log cfu/g and 6.68±0.75 log cfu/g in summer and winter respectively whereas the same of exotic Koi were 8.50±0.06 log cfu/g and 6.62±0.74 log cfu/g both summer and winter. The study revealed that bacterial load in winter season complied with ICMSF standard for both types of Anabas testudineus but bacterial load of both types of same species in summer season didn’t comply with ICMSF standard. Higher temperature influenced on bacterial load because a large number of bacteria were found in this season. The observed results were statistically significant for both types of species (p<0.05) and as well as seasons (p<0.05). The highest bacterial load was observed at the highest temperature (36.3 0 C) in the month of April and the lowest was found at the lowest temperature (18 0 C) in the month of January. Temperature was positively correlated with both indigenous and exotic Koi in both the seasons. The mean Total Coliform (TC) of indigenous and exotic Koi in summer was 197 and 172, in winter 93.4 and 87.1 MPN/g. Total Coliform in winter season complied with ICMSF standard but TC in summer didn’t comply with this standard. The highest TC was found in indigenous Koi (290 MPN/g) in summer season whereas the lowest (34 MPN/g) was in exotic in winter season. The isolated pathogenic bacteria were Escherichia coli, Salmonella spp., and Vibrio spp. In indigenous koi the percentage of these isolated bacteria were 90%, 80% and 70%, respectively whereas the same in exotic Koi were 80%, 70% and 50% in summer season. Similarly, in case of indigenous these were recorded 80%, 60%, 50% and the same in exotic Koi were 70%, 50% and 60% in winter season. This findings of this study indicated that the prevalence of all types of observed bacteria were lower in exotic Koi than indigenous in summer and almost the same results in winter. The studied varieties of Anabas testudineus (indigenous and exotic) were more or less contaminated but comparatively higher bacterial load and pathogenic bacteria in indigenous Koi than exotic Koi both summer and winter season. The results of this study indicated that the TVC, TC and all other identified pathogenic bacteria were higher in indigenous Koi both summer and winter than exotic of the both seasons. The result which don’t comply the ICMSF standard is alarming for food safety as well as not considered for export.