en fish disease fish disease پژوهشي Orginal research papers <p> The development of shrimp aquaculture, in spite of its global necessity, is largely at stake as significant ecological and pathological problems are increasing in the vast majority of the shrimp producing countries. Shrimp immunology is a key element in establishing strategies for controlling diseases in shrimp aquaculture. The total haemocyte count (THC), differential haemocyte count (DHC), total plasma protein (TPP), Phagocytic activity (PA), bacterial clearance efficiency (BCE) and bactericidal activity (BE) were examined when the <i>F. indicus</i> shrimps (11.32±1.20 g) were immersed in seawater (39pptand 25 ± 1 ^○C) containing hot-water extracts of brown alga <i>Sargassum glaucescens</i> at 100, 300 and 500 mg/l. These parameters increased significantly (<i>p</i> < 0.05) when the shrimp were immersed in seawater containing hot-water extracts at 100 mg/l after 3h and 300 and 500 mg/l after 2 h. <i>F. indicus</i> shrimps that were immersed in hot-water extracts at 300 and 500 mg/l had increased phagocytic activity and clearance efficiency to <i>Vibrio spp.</i> after 2 hours. But bactericidal activity increased significantly after 1 hour in the same concentrations. </p> Fenneropenaeus indicus; Sargassum glaucescens, Total haemocyte count, Differential haemocyte count, Total plasma protein, Phagocytic activity, Bacterial clearance efficiency 616 630 http://jifro.ir/browse.php?a_code=A-10-1-119&slc_lang=en&sid=1 B. Ghaednia babak.ghaednia@gmail.com 10031947532846001913 10031947532846001913 Yes M. R. Mehrabi 10031947532846001914 10031947532846001914 No M. Mirbakhsh 10031947532846001915 10031947532846001915 No V. Yeganeh 10031947532846001916 10031947532846001916 No P. Hoseinkhezri 10031947532846001917 10031947532846001917 No G. Garibi 10031947532846001918 10031947532846001918 No A. Ghaffar Jabbari 10031947532846001919 10031947532846001919 No