en Treatment stategies with herbal or others Treatment stategies with herbal or others پژوهشي Original research papers <p dir="ltr" style="text-align: justify;">Shrimp aquaculture has expanded rapidly in many countries and this rapid development resulted diseases outbreaks and further considerable utilization&nbsp; of antibiotics. Use of natural products as antimicrobial has been reported as a resolution problem. The crude extract of a red seaweed (<em>Laurencia snyderiae)</em> collected from the Persian Gulf was evaluated for shrimp growth performance and to determine in vivo efficacy of this seaweed to prevention of&nbsp; shrimp Vibriosis. The ethanol extract of<em> Laurencia snyderiae </em>was not toxic to the Artemia in star- I when it was fed to them for enrichment.&nbsp; The white shrimp (<em>Litopenaeus vannamei) </em>Juveniles fed with these enriched Artemia at 0 mg mL-1 (Control group), and three treatments of 200 , 400&nbsp;&nbsp; and 600 mg mL-1&nbsp; for a 30 days period. Results showed an increase in survival rate in treatment groups compared with control group but wasn&rsquo;t significantly (P<0.05). Shrimps that fed with enriched Artemia showed a significant in growth parameters compare ing to&nbsp; Control group (P<0.05). The notably lower mortality was observed when these juvenile shrimps were challenged to Vibrio harveyi (after 30 days)&nbsp; in comparison with&nbsp; Control. The&nbsp; results indicated that EELS has a good potential in growth- promoting and antibacterial activity against <em>V. harveyi </em>in which&nbsp; is useful&nbsp; in shrimp aquaculture.</p> red seaweed, Laurencia snyderiae, Litopenaeus vannamei, Vibrio harveyi 1 10 http://ijaah.ir/browse.php?a_code=A-10-35-22&slc_lang=en&sid=1 A Dashtiannasab 10031947532846001386 10031947532846001386 Yes Aquatic Health and Disease Department, Iranian Fisheries Science Research Institute, Agricultural Research, Education and Extension Org., Bushehr, Iran M Mesbah 10031947532846001387 10031947532846001387 No Department of Clinical Sciences, Shahid Chamran University, Ahwaz, Iran R Pyghan 10031947532846001388 10031947532846001388 No Department of Clinical Sciences, Shahid Chamran University, Ahwaz, Iran S Kakoolaki 10031947532846001389 10031947532846001389 No Aquatic Health and Disease Department, Iranian Fisheries Science Research Institute, Agricultural Research, Education and Extension Org., Tehran, Iran