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This study aimed to evaluate the potential of oregano oil as a growth promoter for the yellowtail tetra, Astyanax altiparanae. The fish (1.46 ± 0.09 g) were distributed into twenty‐four 60‐L aquaria at a stocking density of 0.5 fish/L. Six isonitrogenous (350 g crude protein/kg) and isocaloric (4272 kcal gross energy/kg) diets containing 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 g/kg of oregano oil were evaluated. At the end of 90 d there was a quadratic effect of oregano oil levels for weight gain, specific growth rate, protein efficiency ratio and carcass weight, and the estimated values to maximize these variables were between 0.2 and 0.6 g/kg. There was also a quadratic effect on the feed conversion ratio, and the estimated value to improve this variable was 0.62 g/kg. A positive linear effect of the treatments was observed for muscle glycogen. With increased levels of oregano oil in the diet, there was a reduction in dry matter and ether extract and an increase in the protein content of the carcass. Thus, it can be concluded that oregano oil, at the level of 0.5 g/kg, acts as a growth promoter for A. altiparanae by improving growth performance and carcass composition.

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.

We aimed to evaluate the effects of Curcuma longa as growth promoter, skin pigmentation enhancer, and stress reducer in diets of Trichogaster labiosa after transport. We used five diets containing 0.0, 1.0, 5.0, 10.0, and 25.0 g kg −1 of turmeric rhizome powder. We observed quadratic effects of turmeric supplementation for feed intake, weight gain, final length, and specific growth rate. The estimated amount of turmeric that decreased these variables ranged from 15.53 to 16.39 g kg −1 . Quadratic effects of supplementation of turmeric for cyan and black dorsal skin coloring indices were observed, with estimated values that increased these variables equal to 15.03 and 17.44 g kg −1 , respectively. After fish transport, quadratic effects of turmeric were observed for the cyan and black dorsal skin depigmentation indices, with estimated values that increased these variables equal to 13.29 and 17.04 g kg −1 , respectively. These results demonstrate that supplementation with turmeric at levels up to 17 g kg −1 causes further reduction in skin color due to the stress of transport. Thus, Curcuma longa acts neither as a growth promoter nor as a stress reducer for Trichogaster labiosa. Curcuma longa does not improve the orange pattern of skin pigmentation in the strain of T. labiosa orange thick-lipped gourami. How to cite: Nascimento, L. S.; Reis, S. M.; Ferreira, P. M. F.; Kanashiro, M. Y.; Salaro, A. L. and Zuanon, J. A. S. 2019. Effects of Curcuma longa rhizome on growth, skin pigmentation, and stress tolerance after transport of Trichogaster labiosa. Revista Brasileira de Zootecnia 48:e20160282.