Empirical comparison of toxic lead accumulation between scaled (Cyprinus carpio) and scaleless (Pangasius hypophthalmus) fish species: A religious approach

A number of experimental studies have reported that the absence of scales in some scaleless fish species causes toxins to absorb faster in the fish body including the skin, muscles and other organs, possibly leading to potential considerable impacts on the consumers. Although numerous researchers studied heavy metal pollution in aquatics, in vitro comparison of heavy metals uptake in the scaled fish, common carp, with the scaleless striped catfish, and also the role of scale coverage in heavy metals absorption are absent. First, lethal concentration (96 h LC50) was determined for each species. Then the fish were exposed to sub lethal concentrations (10% of LC50 values) of Pb at triplicate treatments for 15 days. The examined tissues from each species were sampled at day 15 of the experiment. Following chemical digestion, each tissue was analyzed by atomic absorption unit (Model Thermo) to measure heavy metal concentration. Final contents of Pb in the catfish's tissues were 1.63 times those in the carp’s (excluding the scales). The catfish's muscle amassed 14.6 times Pb than that of the carp. Lead residual in carp’s aquaria was much higher than that in the catfish’s signifying comparably lower metal absorption by carp’s tissues. The experimental results indicate much lesser lead accumulation in carp's muscle due to its scaly skin compared to scaleless skin of catfish. Hence, the scaled body provides an effective protective layer against environmental chemical contaminants, which can justify the consumption of scaly fishes with presumably rather safer muscle.