Immunological findings
Cellular and humeral innate parameters
All of the fish groups fed on KDF showed a significant increase (p < 0.05) in the innate immunological parameters versus those of the control group. The statistical analysis strongly favoured the 0.2–0.3% KDF-treated groups. The findings of the cellular innate immunity exhibited a significant increase (p < 0.05) in phagocytic activity (82.13%) and index (1.8) in the fish group fed on 0.3% KDF compared with the control groups, which had (52.16%) phagocytic activity and (1.49) phagocytic index (Fig. 1). The NBT reduction activity showed a similar pattern. The fish group fed on 0.3% KDF recorded the highest optical density, 1.75 versus 0.819 in the control group. The highest lysozyme activity both in the fish serum and the intestinal mucus was recorded in the 0.3% KDF group, compared with the results for the control group (Table 5).