Hepatoprotective action of including (<i>Euterpe oleracea</i> Mart.) in the diet of Koi carp (<i>Cyprinus carpio</i>)

This study evaluated the hepatoprotective effect of açaí inclusion in the diets of juvenile Koi carp ( Cyprinus carpio ). For the experimental trial, 240 fish were distributed across 20 tanks (n = 12), using a completely randomized design that involved four treatments and one control group. The tested diets were: control (DC0.0%) with no açaí; 0.5% açaí (DA0.5%); 1.0% açaí (DA1.0%); 1.5% açaí (DA1.5%); and 2.0% açaí (DA2.0%) inclusion. The açaí-supplemented diets showed higher concentrations of phenolic compounds, tannins, and flavonoids, as well as superior antioxidant potential compared to the control group (p<0.05). After 30 days of feeding, four specimens from each tank were collected for histological analysis. The analysis of variance at 5% significance revealed a significant difference in the loss of the hepatic cord arrangement, with a reduction of 62.50 ± 13.06% in the control group (DC0.0%) compared to the other treatments. The DA2.0% diet exhibited greater congestion in the sinusoids (54.17 ± 20.87%) compared to the control (33.33 ± 11.68%). The control group also showed a higher number of mononuclear inflammatory infiltrates (72.92 ± 7.54%). Necrotic areas were more intense in the control group (64.58 ± 12.87%) and less pronounced in the DA1.5% diet (43.75 ± 24.13%). The results suggest that diets with intermediate levels of açaí can exert a hepatoprotective effect on Koi carp, indicating that diets with the inclusion of açaí for carp can help in growth and nutrient assimilation, since the liver tissue metabolizes a large amount of the substance, but additional studies are needed to determine the ideal dose and explore its application in other fish species.