Histopathological alterations of the liver, kidney, intestine and gills of farmed rainbow trout (OncorhynchusMykiss) fed a diet containing 1% powder of Aloe vera extract

Despite the increasing use of Aloe vera in aquaculture, toxicity and possible side effects have not been studied in rainbow trout. The aim of this study was to investigate the possibility of some tissue change in farmed rainbow trout (Oncorhynchusmykiss) fed with feed containing 1% of hydro-alcoholic extract of Aloe vera. Six hundred pieces’ healthy fish, average means 13 grams were randomly allocate into 2 groups, including Aloe vera extract-treated (1%) and control (placebo 1%), each of triplicates. Their feed has been previously prepared. At the end of the tenth week, 2 fish pieces was caught in each replicate. After anesthesia, the fish were autopsied. The liver, intestine, kidney and gills of fishes were removed. Specimens were fixed in 10% formalin, stained by using Hematoxylin and Eosin (H&E). Finally, prepared tissues were evaluated by optical microscopy. The results were no shown any changes in intestinal histology in the Aloe vera extract-treated group. However, melanomacrophage centers development was observed in liver and kidney in some fish's Aloe vera extract-treated. Such limited tissue changes were natural reaction of studied tissues to the foreign matter (xenobiotics). Some of the gill specimens in both groups showed epithelial cells hyperplasia in primary gill lamella, which is no related to medicinal treatment. It was possibility concern to environmental conditions and water quality. Based on the above findings, it seems that the selected dose of Aloe vera extract has not been detrimental to vital organs of fish in this research study.