This study aimed to evaluate the effect of oregano oil on the intestinal and liver morphometry of yellow tail tetra, Astyanax altiparanae. Fish (1.46 ± 0.09 g) were kept in a 60-L aquaria, at a stocking density of 0.5 fi sh L -1 . Six diets containing varying amounts of oregano oil were evaluated (0.0; 0.5; 1.0; 1.5; 2.0 and 2.5 g of oregano oil kg -1 ). At the end of 90 days, the fi sh were euthanised. Four intestines and four livers were collected per treatment, which were fi xed in Bouin and embedded in resin. For height and width folds, the absorption surface area and thickness of the muscular layer a positive linear effect of oregano oil was observed. A decrescent linear effect on the total number of goblet cells was also observed. For the cytoplasmic percentage of hepatocytes and liver glycogen, a positive linear effect of oregano oil was observed. There was a decreasing linear effect on the percentage of nuclei in the hepatocytes and capillaries. Thus, the oregano essential oil promotes increased absorption areas, modulates the amount of goblet cells involved in protecting the intestinal mucosa and promotes cytoplasmic increase with greater deposition of liver glycogen in yellow tail tetra.

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The aim of the present study was to evaluate the effect of turmeric (Curcuma longa) as additive in the diet for Astyanax aff. bimaculatus. Fish (0.83 ± 0.04 g) were fed, for 60 days, with six diets containing 0.0, 20.0, 40.0, 60.0, 80.0, and 100.0 g turmeric kg feed. There was an increasing linear effect of turmeric on the thickness of the muscular layer, and height and width of the folds of the intestine. In the liver, a quadratic effect was observed of turmeric on the percentage of hepatocyte cytoplasm and a decreasing linear effect on the percentage of sinusoid capillaries. A quadratic effect was also observed of turmeric on the liver glycogen. There was no effect of turmeric on the antioxidant activity in the liver, carcass composition or productive performance of the fish. Thus, we concluded that Curcuma longa has trophic effects on the epithelium and the muscular layer of the intestine of A. aff. bimaculatus. Additionally, low levels of Curcuma longa cause increased deposition of liver glycogen and high levels cause reduction.

With this study, we aimed to assess the safety of using Curcuma longa in fish feed. Juvenile Astyanax aff. bimaculatus (0.83 AE 0.04 g) were kept in 24 80-L aquaria, at a density of 0.5 fish L À1 for 60 days. Six diets supplemented with 0.0, 20.0, 40.0, 60.0, 80.0 and 100.0 g kg À1 were evaluated. Histopathological analysis of the gills showed that there was an increasing linear effect of turmeric on the frequency of lamellar aneurysm, hypertrophy of mucous cells, oedema and necrosis. There was a quadratic effect of turmeric supplementation on the frequency of fusion and disruption of secondary lamellae, vacuolation and hypertrophy of the epithelial cells, and the estimated values to minimize these variables were 4.63, 25.93 and 24.46 g kg À1 respectively. There was a quadratic effect of turmeric on the gills index (I BRA ), and the estimated value to minimize this index was 30.23 g kg À1 . No effect of turmeric on the frequency of histopathological changes and organ index in fish liver was observed. Thus, we conclude that turmeric is not hepatotoxic for A. aff. bimaculatus; however, its use is safe at concentrations up to 30.23 g kg À1 diet as a function of its gill toxic effect at higher doses.