en fish disease fish disease پژوهشي Orginal research papers The efficacy of neem (<em>Azadiracta indica</em>) against <em>Lernaea cyprinacea </em>was studied. Two types of neem seeds powder, <em>viz</em>; (1) dried and powdered neem seeds and (2) solvent extracted neem seeds powder prepared by treating dried seeds powder with petroleum ether were used in the present study. These experiments were carried out in the month of August 2014. Different types of extracts were prepared by separately solubilising both types of neem` seeds powder in i) 1% NaCl solution and (ii) water at two temperatures (28 <sup>o</sup>C and 90<sup>o</sup>C). These extracts were tested at varying concentrations (10, 25, 50 and 100 &micro;g mL<sup>-1</sup>) against <em>Lernaea</em>. Results indicated that neem seeds powder treated with solvent and further solubilized with hot water (90<sup> o</sup>C) at a concentration of 100 &micro;g mL<sup>-1</sup> was effective in preventing the hatching of <em>L.cyprinacea</em> eggs and their further development. Nauplii and copepodid-I stages were also exposed to above mentioned neem seed extracts at a concentration of 100&micro;g mL<sup>-1</sup>. Nauplii became inactive within 2 hrs and copepodids died after 43 minutes exposure to solvent treated neem`s powder extracted with hot water. Fishes (<em>Labeo fimbriatus)</em> survived for an average period of 5 and 30 min in all types of neem seeds extracts except the one extracted with water at 28^oC (both solvent treated and untreated neem`s seeds powder).&nbsp; Nauplii, Copepodid, Lernaea cyprinacea, Azadiracta indica, Labeo fimbriatus. 1864 1870 http://jifro.ir/browse.php?a_code=A-10-2001-1&slc_lang=en&sid=1 A. Raghavendra raghuckm9@gmail.com 100319475328460036119 100319475328460036119 Yes Peninsular Aquaculture Division of Central Institute of Fresh water Aquaculture, Hesaraghatta Lake Post, Bangalore-560089, Karnataka, India R.S. Jaswal ravisjaswal@gmail.com 100319475328460036120 100319475328460036120 No Peninsular Aquaculture Division of Central Institute of Fresh water Aquaculture, Hesaraghatta Lake Post, Bangalore-560089, Karnataka, India K.P. Hemaprasanth hpcifa@yahoo.com 100319475328460036121 100319475328460036121 No Peninsular Aquaculture Division of Central Institute of Fresh water Aquaculture, Hesaraghatta Lake Post, Bangalore-560089, Karnataka, India C.B. Soumya cbsoumya323@gmail.com 100319475328460036122 100319475328460036122 No National Bureau of Agricultural Insect Resources, H.A.Farm Post, Bellary Road, Hebbal, Bangalore-560024, Karnataka, India