~ 414 ~ International Journal of Fisheries and Aquatic Studies 2021; 9(1): 414-419 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 (GIF) Impact Factor: 0.549 IJFAS 2021; 9(1): 414-419 © 2021 IJFAS www.fisheriesjournal.com Received: 14-11-2020 Accepted: 26-12-2020 Clara Bindu F Unit of Toxicology, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India Anila P Ashokan Unit of Toxicology, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India Sutha J Unit of Toxicology, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India Dr. Ramesh M Professor, Unit of Toxicology, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India Corresponding Author: Dr. Ramesh M Professor, Unit of Toxicology, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India Sub-lethal toxicity of alphamethrin on biochemical indices in a freshwater fish, Cyprinus carpio Clara Bindu F, Anila P Ashokan, Sutha J and Dr. Ramesh M DOI: https://doi.org/10.22271/fish.2021.v9.i1e.2428 Abstract The focus of the study is to evaluate the effects of a pyrethroid pesticide, alphamethrin on freshwater fish Cyprinus carpio. The LC50 of alphamethrin for 96 h was determined as 6 μg/L. For sub-lethal study, 1/10 th (0.6 μg/L-Treatment I) and 1/5 th (1.2 μg/L-Treatment II) of 96 h LC50 concentration were exposed to C. carpio for 35 days. At each interval period, biochemical responses such as plasma glucose, protein and muscle glycogen were determined. During the study period, plasma glucose level was significantly increased with decrease in plasma protein in both the treatment groups. The muscle glycogen content in the fishes treated with 0.6 μg/L and 1.2 μg/L of alphamethrin were also observed to decrease significantly. The overall study concludes that alphamethrin at sublethal concentration affects the biochemical indices of Cyprinus carpio. The changes in these biochemical indices can be effectively used to monitor the alphamethrin pesticide in the aquatic environment. Keywords: Pesticide, synthetic pyrethroids, sub-lethal toxicity, freshwater fish, glycogen 1. Introduction Pollution has been regarded as one of the most severe menaces to the environment, including heavy metals, pesticides, sewage, oil, etc. in both freshwater and marine environment [1]. Over the world-wide ranges, pyrethroids pesticides have a high biological action and low rapid toxicity compare to the other pesticides (organochlorine and organophosphate) [2] . However, the concentration of residues in aquatic environments has increased with the wide application of pyrethroids pesticides, threatening the health of the aquatic animals [3, 4] . With the restriction of organophosphorus pesticides, synthetic pyrethroids have begun to occupy the market, accounting for 38% of the global pesticide market [5] . Of these pyrethroid insecticides, alphamethrin is extensively used for a wide range of crops in agriculture because it causes high toxic effect on a broad spectrum of insect pests. Alphamethrin is commonly and effectively used on cotton, cereals, pulses, vegetables, fruits, oilseeds, tea, tobacco and other crops. Although alphamethrin is considered safe for human beings and mammals, long-term and large-scale use of it poses a potential hazard to both natural environment and non-target organisms. The synthetic pyrethroid insecticide alphamethrin is not only used in agricultural practices during crop production, but also in public health programs and as an ectoparasiticide in animals. This account for 30% of global pesticide consumption [6] . Alphamethrin have been reported to damage vital organs of various target and non-target species [7] , also reduces reproductive ability [8] in fishes. Sarikaya [9] has reported that the 96 hr LC50 value for Nile tilapia was found to be 5.99 μg/L showing that it is a highly toxic synthetic pyrethroid pesticide. The seepage of this insecticide into water bodies, enter the food chain and leads to its accumulation in the tissues of the aquatic organisms of higher tropic levels like fish. The toxicity of alphamethrin in fish can be due to rapid absorption through gills and, the lacking of enzymatic system to hydrolyse these pesticides [10] . Alphamethrin was found to cause changes in reproductive and oxidative metabolism of Lymnaea acuminate [11] which may be due to inhibition of sodium channels of cells. Fish accumulate various fold higher concentration of chemical pesticide residues than the surrounding water in aquatic environment. Severe contamination of aquatic environment by chemical pesticides can cause chronic and acute poisoning of fish and other organisms [12-14] .