Piscicidal Activity and Phytochemical Analysis of Effective Herbs of Nepal
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Department of Zoology
Abstract
The freshwater fish Clarias batrachus(Linnaeus) of the family Clariidae locally known as Mangur is one of the stronger fish having accessory respiratory organs. Organophosphates and organochlorine poisons are commonly used for fishing is highly toxic stable compounds remain stored in fish tissue. In Nepal, many fish stupefying plants are used to stun fish that is comparatively safe for human consumption. Indigenous five plants are used for killing fish namely, Agave americana(Ketuke),Budhleia asiatica(Bhim senpati),Euphorbia royleana(Siundi),Madhuca indica(Mahua),Sapium insigne(Khirro). These plants were collected from Kathmandu and Kapilvastu. Samples were air dried, powdered and extracted with 50% methanol by soxhlet method.
Comparative toxicity at 500 ppm concentration and toxic strength at different concentrations of most toxic herb was performed. Ten fishes were stocked to each of the experimental boxes and a control box in replicates and toxicity test lasted for every 24 hours. Based on the 24 hours lethal dose (LD
) the plants extract with the toxicity toC. batrachus of the plants arranged in the order of decreasing toxicity as follows: S. insigne>E. royleana>M. indica and for 48 hours B. asiatica>A.americana.
The work also provides coverage of phytochemicals (alkaloid, tannin,saponin, flavonoid, steroid, cardiac glycoside, terpenoid and phenols) present in the plant samples. The chemical parameters after and before the extract application were analyzed to know the fluctuation in parameters of aquarium water. The quantity of oxygen is drastically decreased from 13.28 ppm to 2.81 ppm below the standard level after the application of extract and the ammonia level is increased from 0.6 ppm to 3 ppm beyond standard level. The mortality percent of fishes due to the application of herbal extract compared with Nuvan insecticide (62.5 ppm).
The results of the study showed that locally available plants in Nepal have potential to be used as piscicide which can be an alternative to harmful chemical piscicides.