Bioassay on Metal Silver and Toxicity Studies in Freshwater Fish Cyprinus carpio

Silver is a noble metal that has a high electrical conductivity, heat stability and special properties. Silver is present in different forms in the environment especially in the living organisms. Silver has been utilized in jewellery, monetary currency and photography and is known to have an antibacterial effect. The toxic effect or heavy metal poisoning is defined as, a functional or morphologic change in the body produced by an ingested, injected, inhaled or absorbed drug, chemical, or biological agent. Argyrosis is pathologic bluish-black pigmentation in a tissue resulting from the deposition of an insoluble albuminate of silver. Fish are ideal sentinels for behavioral assays of various stressors and toxic chemical exposure due to their constant, direct contact with the aquatic environment where chemical exposure occurs over the entire body surface. Toxicological studies of the pollutants upon aquatic organisms are very important from the point of environmental consequences. Bioassay can be defined as a test to evaluate the relative potency of a chemical by comparing its effect on a living organism with that of standard preparation. In the present investigation the median lethal concentration (LC 50) of Silver to an Indian major carp Cyprinus carpio for 24 and 96 hours were found to be 1.5 mg/L and 0.75 mg/L.