Journal of Environmental Biology

Acute toxicity bioassay of dimethoate on freshwater airbreathing catfish, Heteropneustes fossilis (Bloch)

Rakesh K. Pandey*¹, Ram N. Singh¹, Sarika Singh¹, Narendra N. Singh² and Vijai K. Das¹

¹Department of   Zoology, Kamla Nehru Institute of Physical and Social Sciences, Sultanpur - 228 118, India

²Department of Zoology, St. Andrew’s College, Gorakhpur - 273 001, India

(Received: June 26, 2007; Revised received: November 10, 2007; Accepted: December 25, 2007)

Abstract: Pesticides are chemicals used for pest control in the agricultural fields. They finally reach the surrounding water bodies through surface runoff affecting the aquatic fauna. Dimethoate is frequently used organophosphate pesticide due to its high effectiveness and rapid breakdown into environmentally safe products. A 96 hr static acute toxicity test was carried out to determine the LC₅₀ value of dimethoate, on the freshwater airbreathing catfish Heteropneustes fossilis (Bloch). The fish were exposed to 7 different concentrations of dimethoate (2.50, 2.75, 3.00, 3.25, 3.50, 3.75 and 4.00 mg l^-1) for toxicity bioassay. Control (0.00 mg l^-1) was also carried out. The data were subjected to Finney’s Probit analysis and processed with Trimmed Spearman-Karber statistical software. The LC₅₀ values for dimethoate for 24, 48, 72 and 96 hr were 3.38, 3.23, 3.08 and 2.98 mg l^-1, respectively. At higher concentration of dimethoate (3.25 mg l^-1 and above) the fish showed uncoordinated behaviour such as erratic and jerky swimming, attempt to jump out of water, frequent surfacing and gulping of air, decrease in opercular movement and copious secretion of mucus all over the body.

Key words: Acute toxicity, dimethoate, LC₅₀ mortality, Heteropneustes fossilis

PDF of full length paper is available with authors (* rakesh_zoology@yahoo.co.in )

Copyright © 2009 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).