Contaminants In Fish

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Natural aquatic bodies are being polluted due to untreated effluents released from agricultural, industrial and sewage waste waters. These pollutants are harmfully affecting the aquatic life, including fish (Gagnaire et al., 2004). Among aquatic pollutants, there exist organic and inorganic compounds such as combustible substances, petroleum products, phenol, textile dyes and heavy metals. Among inorganic contaminants, heavy metals are the prominent ones (Jadhavet al., 2010). Fish are more susceptible to the harmful impacts of pollutants and serve as an excellent tool for understanding the health status of aquatic ecosystem (Donohue et al., 2006). Fish can uptake heavy metals from the surrounding environment that can accumulate in various organs …show more content…

There have been numerous reports of histopathological changes in the liver and kidney of the fish exposed to a wide range of heavy metals and organic compounds (Abdel, 2012). Impact of contaminants and toxicity of heavy metals in aquatic ecosystem can be evaluated by measuring physiological and biochemical parameters in the kidney and liver of the fish (Barhoumi et al., 2012). In comparison to the terrestrial life, aquatic organisms are more sensitive to the exposure and toxicity of heavy metals, therefore, they provide the accurate data to analyze the lethal effects such as, mutagenicity and oxidative stress caused by environmental pollutants (Vosyliene and Jankaite, 2006). Oxidative stress is a difference between the rate of production of reactive oxygen species and antioxidant defense system of the aquatic organisms (Nishida, …show more content…

Elevated levels of heavy metals, like zinc and lead, in the tissues of the fish can produce reactive oxygen species such as hydrogen peroxide, superoxide radicals and hydroxyl radicals that can cause apoptotic cell death by disrupting normal enzymatic pathways (Cao et al., 2010). Antioxidant enzymes are natural compounds that are protein in nature and they are important in sustaining animal life against ROS (Norberg and Arner, 2001). For protection of cells, antioxidant enzymes such as catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH) and glutathione-S-transferase (GST) play a vital role in reducing the oxidative stress (Pereir et al., 2010). Peroxidases are broadly present in the microorganisms and animal tissues. When oxidative stress increases, peroxidase functions as first line of defense against reactive oxygen species (Boeuf et al., 2000).
The Catla catla commonly called thaila, is an important major carp due to its easily availability, higher growth rate, consumer preference and its compatibility with other major carps (FAO, 2005). In the field of ecotoxicology, the use of oxidative stress biomarkers are gaining importance as they could provide an early warning to the potentially hazardous substances in the aquatic environments. Therefore, during present

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