en aquaculture aquaculture پژوهشي Orginal research papers <span style="font-size:11pt"><span style="line-height:109%"><span style="tab-stops:301.5pt"><span style="font-family:Calibri,sans-serif"><span lang="TR" new="" roman="" style="font-family:" times=""><span style="color:black">This study aimed to examine the effect of fatty acid in the diet on changes the incidence of the Red-head Syndrome under temperature stress and hypoxia in white leg shrimp (<i>Litopenaeus vannamei</i>) during 8 weeks. For this purpose, shrimps were fed&nbsp; by 4 diets&nbsp; (diet 1: containing 7.02% of total fat; diet 2: containing 6.41% of total fat; diet 3: containing 8.05% of total fat; diet 4: containing 6.41% of total fat with 1750 mg/kg of vitamin E), under 3 stressors (S1: no challenge to environmental stresses; S2: with hypoxic stress (2.0&plusmn;1.0 ppm); S3: with increasing temperature stress (36&plusmn;2&deg;C). The results of the hypoxic stress on the incidence of redness in <i>L. vannamei</i> fed with different levels of fatty acids showed that there were differences significantly (<i>p</i><0.05). Temperature increase although showed no differences between healthy shrimps(<i>p</i>>0.05) but, there were significant difference among red-headed shrimp in treatment 1, 2 and 3 (<i>p</i><0.05). The examination in treatments 2 and 3 showed hepatopancreatic &nbsp;were loss the columnar structure so thatelongated cells and dilated tubules were observed. Some B cells had no vacuoles and were not fully developed. The number of R cells was low and basophilic F cells were convex. In treatment 4, the cells have few reserves and were normal. Some B cells were degenerated. The height of the tubules was lower than normal, but no inflammatory reaction was observed in the tissue. In treatment 4, cell showed&nbsp; better conditions than treatments 2 and 3. Accordingly, B cells were present well and R cells showed moderate storage. In general, it can be concluded that the use of vitamin E can reduce the complication of redness and minimal cell damage to hepatopancreatic tissue in <i>L. vannamei</i>.</span></span></span></span></span></span> Fatty acid, Vitamin E, Redhead, Hepatopancreatic tissue, Litopenaeus vannamei, Environmental stresses 915 930 http://jifro.ir/browse.php?a_code=A-10-3212-3&slc_lang=en&sid=1 S. Mobaraki samira.mobaraki@gmail.com 100319475328460053945 100319475328460053945 No 1Department of Fisheries, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran N. Javadzadeh nargesjavadzadeh@yahoo.com 100319475328460053946 100319475328460053946 Yes 1Department of Fisheries, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran H. Mabudi mikhak1311@yahoo.com 100319475328460053947 100319475328460053947 No 1Department of Fisheries, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran M. Hafezieh jhafezieh@yahoo.com 100319475328460053948 100319475328460053948 No 2Iranian Fisheries Research Organization, P.O. Box: 14155-6116, Tehran, Iran M. Khodadadi mjkhodadadi@gmail.com 100319475328460053949 100319475328460053949 No 1Department of Fisheries, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran