• Asma Yamin

• Saima Naz

• Riaz Hussain

• Tuba Rehman

• Ansar Shaheen

• Ahmad Manan Mustafa Chatha

• Abdul Ghaffar

• Muhammad Ismail Abbas

• Muhammad Sajjad Moazzam

Abstract

The terrestrial and agro-aquatic ecosystems are continuously at the pity of human's negative impacts. Extensive and indiscriminate application of agrochemicals like heavy metals, industrial wastes, germicides, drug residues and different feed additives has become serious threats to public health. The current experimental trial was executed to investigate genotoxic potential of different heavy metals in fresh water fish (Labeo rohita). Methods: A total of 120 active, healthy, free from disease and internal parasites fish having three months of age were procured from local fish breeding center and were kept in glass aquarium having 100 liter water. After two weeks of acclimatization, fish were arbitrarily distributed and placed in different eight groups (A-H). Prior to start of experiment, acute toxicity of various heavy metals alone such as lead, cadmium, chromium and in combination (Pb +Cr), (Cr+Cd), (Cd+Pb) and (Pb+Cr+Cd) mixture were determined in-term of 96-h LC50 and lethal doses for Labeo rohita. After assessment of acute toxicity, all the fish were exposed to three sub-lethal concentrations (5, 7 and 9%) of heavy metals alone and in combinations for a period of 30 days in triplicate experiments. Results: Different clinical ailments like, increased surface breathing, loss of coordination, rapid opercular movement, erratic swimming, air gulping, jerking movement and tremors were noted in fish. Histopathological observations of gills of various fish exhibited severe microscopic alterations. Results on micronucleus assay exhibited increased frequency of formation of micronuclei in red blood cells, while comet assays showed significantly increased DNA damage in peripheral erythrocytes in-term of arbitrary units of comets, average percentile rate of damaged cell and genomic damage index. Conclusion: From the results of our experimental study, it can be concluded that fresh water fish are useful and reliable bio-indicators of heavy metal toxicity. Micronucleus and comet assays showed that heavy metals alone and in combination induced DNA damage in fish.

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