Proximate Composition and Bioaccumulation of Selected Heavy Metals in Muscle Tissues of Two Fish Species from the Balu River, Bangladesh

Abstract

The proximate composition and heavy metal accumulations in the muscles of two important fish species, Catla catla and Labeo rohita, were evaluated from the Balu River, Bangladesh. Samples were collected and analyzed for proximate composition and heavy metal using standard methods. Moisture content was the highest in both species, measuring 74.43% in Catla catla and 75.70% in Labeo rohita, whereas ash content was the lowest, at 1.98% and 2.04%, respectively. Varying levels of the selected metals were detected, with a higher concentration of Pb in L. rohita and a lower concentration of Cr in L. rohita. Cd was not detected in either of the fish species. Level of proximate composition and heavy metal content in both species were as follows: Moisture>Protein>Lipid>Ash, and Pb>Cr>Cd. Correlation analysis revealed a strong inverse relationship between protein and moisture content (r = -1.00) and between Pb and Cr concentrations (r = -1.00), suggesting antagonistic metal accumulation behavior. Opposing PC1 scores (-1.414 and 1.414) for proximate composition, and (-1 and +1) for heavy metal content clearly separated the two species. Safety assessment analyses (THQ and HI) showed that detected metal levels in both species exceeded safe limits, indicating these fish species are unsafe for human consumption.

Keywords: proximate composition, Heavy metal, bioaccumulation, Balu River, Bangladesh