Observation of heavy metals accumulation and growth performance of Koi, Anabas testudineus(Bloch, 1792) by using different market feeds

Abstract

The study was conducted to determine the concentration of heavy metals in some commonly used commercial fish feeds. This study also observed the bioaccumulation of Cr, Cu, Cd, Pb and Ni in fish organs such as intestines, muscle and gills of Koi (Anabustestudineous)after culturing them for twelve weeks by using differentmarket fish feeds. The present study showed that concentration (33.42 mg/kg) of Ni was found the highest in Madina feed among five heavy metals that exceeded the permissible limit set by FAO. In cultured Koi, the concentration of studied heavy metals was found higher than initial concentration in fish feeds and collected fingerling samples. Metal levels in cultured fish followed the ranking: Cu >Pb> Cr > Cd > Niand order of bioaccumulation in individual organs was intestines > gills > muscle. The highest concentration (368.67mg/kg) of Cu observed in intestines of Koi given Madina feed and the lowest concentration (14.03 mg/kg) was recorded in muscle of Koi receiving Quality feed. The highest concentration of Pb (138.28 mg/kg) observed in intestines of Koi givenMadina feed and the lowest concentration (0.00 mg/kg) was recorded in muscle of Koi receiving Quality feed.Bioaccumulation of Cr (3.20 mg/kg) was the highest in gills of fishes taken Mega feed and the lowest (0.00 mg/kg) in intestine of Koi cultured with different feeds.The concentration of Cu, Pb and Cr exceed the tolerable limit in fishes cultured with the experimental feeds. The concentrations of Cd,and Ni were below the permissible range approved by FAO. As Koi fingerlings were cultured, the growth performance parameters like condition factor (K), average daily gain (ADG), specific growth rate (SGR) and feed conversion ratio (FCR) were also determined in different feeding levels. The highest condition factor was observed at 30th day period in Handmade feed (B3) as 3.13±0.20 and lowest was observed at 60th day period in Quality feed as 1.58±.096. The highest Average Daily Gain (ADG) during the study period was found to be0.11±0.001 at 30th day period in Handmade feed (B3) and the lowest value of ADG was recorded .03±.004at 90th day period in Mega feed. The highest specific growth rate was 4.68±.39 found in Madina feed in 60th day of culture and lowest was determined in 0.80±.01 during 60th day in Handmade feed (B3). The highest FCR value 3.74±0.38 was observed in T1 during 30th day period and lowest FCR value (1.29±0.13) was observed in Quality feed during 90th day period. Considering the present study, Koi cultured with these experimental feeds is not safe for human consumption. Because higher concentrationthan allowable limitof these heavy metalsmight cause harmful effect on human body after consuming those fishes and cancreate cancer and other heavy metal-related diseases on human body.