Histopathology of shrimp fed with algae Gracillaria corticata compared to shrimp fed with commercial in the face of white spot syndrome virus

White spot disease (WSD) is one of the shrimp lethal viral diseases that causes heavy losses on all shrimp of Penaeid family. In this study comparison of histopathological effects of Red algae Gracillaria corticata dietary in shrimp challenged to white spot syndrome virus was investigated. For this aim 1200 SPF white leg shrimp (L. vannamei) sub adult with average weight of 10±1.02 g was collected and divided to four groups. The first group (T1) fed G. corticata powder was mixed with shrimp feed (2 g/Kg), second group (T2) fed G. corticata (2 g/ Kg) and after 14 days injected with WSSV and all groups maintained for 25 days, third group (T3) fed with commercial pellet and fourth group fed with commercial pellet and then injected with WSSV and all group maintained for 25 days. For histopathology survey, the samples of gills, hepatopancreas, lymphoid tissue, stomach and gut were fixed in davidson solution. Tissues were embedded in paraffin wax, sectioned at 5µm and stained with hematoxylin-floxin eosin. The histopathology results indicated that samples fed with algae and positive control in the face of white spot syndrome virus were inclusion body cells observed in gills, stomach, gut and hepatopancreas.  Survival rate in T2 group was higher and significantly different (p < 0.05) from T4.