International Journal of Aquaculture, 2025, Vol.15, No.1, 11-20 http://www.aquapublisher.com/index.php/ija 15 For the analysis of lesions, corresponding values were assigned to the histological alterations: 0 (no alteration), 1 (mild alteration, corresponding to up to 25% of the analyzed tissue area), 2 (moderate alteration, 26%~50% of the tissue area), and 3 (severe alteration, >50% of the tissue area). The intensity grades were used solely to measure the severity of the lesion and were subsequently converted into percentages (%) according to Cardoso et al. (2024). 2.6 Statistical analysis The data was subjected to the Shapiro-Wilk and Levene tests to assess normal distribution and homoscedasticity, respectively. If the data was declared non-parametric, it was transformed. Subsequently, in compliance with the assumptions, the data was analyzed using ANOVA (analysis of variance) and, when appropriate, the means were separated using Tukey's post-hoc test. All tests were carried out at a 5% significance level using Statistica 12.0 software. 3Results The chemical analysis of the diets (Table 2) revealed that phenolic compounds were more pronounced (p > 0.05) in the diets with higher levels of açaí inclusion, DA1.5% and DA2.0% (30.50 ± 0.35 mg/g and 33.07 ± 0.07 mg/g, respectively), compared to the diet without inclusion, DC0.0% (23.40 ± 0.10 mg/g). A similar pattern was observed for flavonoids, with DA1.5% (14.90 ± 0.10 mg/g), DA2.0% (16.60 ± 0.10 mg/g), and DC0.0% (12.00 ± 0.10 mg/g); for tannin content, DA1.5% (1.53 ± 0.06 mg/g), DA2.0% (1.73 ± 0.06 mg/g), and DC0.0% (1.07 ± 0.06 mg/g); and for antioxidant potential concentration, DA1.5% (3.33 ± 0.07%), DA2.0% (3.77 ± 0.06%), and DC0.0% (1.13 ± 0.05%). Table 2 Content of phenolic compounds, flavonoids, tannins and antioxidant potential of the experimental diets. Different letters (a, b, c) in the same line indicate significant difference between treatments by Tukey's post-hoc test (p<0.05) Parameters (mg/g) DA0.0% DA0.5% DA1.0% DA1.5% DA2.0% p value Phenolic compounds 23.40±0.10b 24.23±0.25b 26.40±0.10ab 30.50±0.35a 33.07±0.07a <0.01 Flavonoids 12.00±0.10b 12.47±0.15b 13.03±0.06ab 14.90±0.10a 16.60±0.10a <0.01 Tannins 1.07±0.06c 1.17±0.06c 1.37±0.06b 1.53±0.06a 1.73±0.06a <0.01 Antioxidant potential (%) 1.13±0.05c 2.43±0.06b 2.87±0.06b 3.33±0.07a 3.77±0.06a <0.01 Regarding the histological alterations in the hepatic tissue of koi carp (Table 3), a significant difference (p < 0.05) was observed in the loss of cord-like appearance, which was more pronounced in DC0.0% (62.50 ± 13.06%) (Figure 1A) compared to the other treatments: DA0.5% (50.00 ± 10.66%), DA1.0% (45.45 ± 15.08%) (Figure 1B), DA1.5% (56.82 ± 11.68%), and DA2.0% (54.55 ± 15.08%). The diet DA2.0% resulted in greater congestion in the sinusoidal cords, with 54.17 ± 20.87% (Figure 2A) compared to DC0.0% (33.33 ± 11.68%) and DA1.5% (35.42 ± 12.87%), while DA0.5% and DA1.0% did not differ (p > 0.05) from the other diets, showing 46.88 ± 8.84% and 43.75 ± 15.54%, respectively. The control group exhibited a higher concentration (p < 0.05) of mononuclear inflammatory infiltrates, at 72.92 ± 7.54% (Figure 2B), compared to DA1.0% (54.17 ± 20.87%) and DA1.5% (50.00 ± 21.32%), but no significant difference (p > 0.05) was found concerning the other inclusion levels. Figure 2 Arrows indicate sinusoidal congestion in the liver tissue of koi carp at DA2.0% (A); Ellipse shows mononuclear inflammatory infiltrate (purple dots) in a large vessel in the liver tissue of koi carp at DC0.0% (B); Tukey (p<0.05)
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