A Comparative Study on Chromium Absorption between Scaled and Scaleless Fish Species: Common Carp (Cyprinus carpio) and Sutchi (striped) Catfish (Pangasius hypophthalmus)

This research aimed at comparison of chromium bioaccumulation patterns in skin, gills, scales, liver and muscle of two widely-consumed fishes: scaled common carp Cyprinus carpio and scaleless catfish Pangasius hypophthalmus. First, lethal concentration (96 h LC50) of chromium as well as its toxicity factor (TF) was determined for each species. For bioaccumulation trial, the two species exposed to sublethal concentrations (10% of LC50 values) of Cr at separate triplicate treatments for 15 days. The examined tissues from each species were sampled at days 7 and 15 of the experiment. Following chemical digestion, each tissue was analyzed by atomic absorption unit (Model Thermo) to measure chromium concentration. According to the results, Almost all differences in bioaccumulations between the two species and the controls were significant (p<0.05). Concentration of chromium in common carp was in the form of gills> liver> skin> scales> muscle, and accumulation in catfish was in the form of liver> muscle> skin> gills. Final entire contents of Cr in the catfish's tissues were 3.65 times, than in the carp’s (excluding the scales). In addition, the catfish's muscle amassed 16.15 times greater amounts of Cr.The results of this investigation indicate that the carp's scaled armature, compared to the scaleless skin of the catfish, adsorbs metal toxicants leading to much lesser metals content in the muscle rendering this tissue rather safer for comestible consumption.