Heavy Metal Accumulation among Different Organs of Cultured Rohu and Catla along with Evaluation of Enzymatic Activities in Examined Organs
Authors: Bin Quader Md Fahad , Fatema Tania Sharmin , Mazed Maria Al , Nur Popy Zannatun , Al Nahid Sk Ahmad , Islam Md Ashraful , Ahmed Sk Istiaque 
Published: March 2022

Aims: The present study was carried out to determine the concentration of heavy metals and to evaluate whether there are any serious toxic effects of the widely exposed heavy metals namely arsenic (As), lead (Pb) and chromium (Cr) in different tissues of two commercially important cultured fish Rohu (Labeo rohita) and Catla (Gibelion catla)

Study Design: The study was designed based on Randomized Block Design (RBD) to avoid all kinds of possible biases as well as for ensuring the representation of different fish farms. Three replications were maintained to deal with the possible errors caused by sampling.

Methodology: Lead (Pb), Arsenic (As) and Chromium (Cr) were analyzed in a graphite furnace (GBCGF 3000 with Zeeman background corrector) with an auto sampler using Atomic Absorption Spectrophotometer (AAS). ALP (alkaline phosphates) activity of liver, Kidney and muscle was assayed using the standard method stated by Garen and Levinthal (1960) [1]. ATPase enzyme activity was determined to follow the standard method stated by Post and Sen (1967) [2]. During each month, ten individuals of the targeted two species each incorporating with three replications were collected from four intended fish farms, with a total of 240 fishes in the study period.

Results: The obtained results stated the highest concentrations of all heavy metals (except arsenic) were recorded in Rohu fish with no significant difference with the other investigated fish species Catla. Organ wise heavy metal concentrations in Rohu (Labeo rohita) fish showed that Lead (Pb) concentrations were higher in all organs compared to other investigated heavy metals. The recorded values of Pb in gills, livers, kidneys, and muscles were 0.021, 0.021, 0.028 and 0.008 ppm respectively. In case of Arsenic (As), the highest concentration was recorded in kidneys while the Chromium (Cr) showed higher accumulation in the muscles. While it comes to Catla (Gibelion catla) fish, similar results were demonstrated where Lead (Pb) concentration was the highest and Chromium (Cr) concentration was lowest. Among all the three heavy metals, the accumulation trend of Arsenic (As) was found highest in gills of Catla (Gibelion catla) but Lead (Pb) and Chromium (Cr) were accumulated in high concentration in kidneys of the same species. The average concentration of different heavy metals in the two investigated fishes were lower than the standard recommended value (0.01ppm) except for Arsenic (As) in Catla (Gibelion catla) which was 0.013ppm. Enzymatic activities like ATPase and ALP were recorded highest in kidney tissue and the lowest in muscle in case of both fish species.

Conclusion: Even though the average values of Arsenic in Catla (G. catla) fish was slightly higher than the recommended value suggested by WHO [3], the concentration is lower in edible part muscle which in turn indicates that the cultured Rohu (L. rohita) and Catla fishes in the Chattogram region are safe for human consumption.