In contrast, the Shannon–Wiener indices for the two diets were similar (Table 7). Among individual genera of bacteria, Acinetobacter, Aeromonas, Pseudomonas, and Shewanella were more abundant in fish from the LOW system than the MOD system (Table 7). In contrast, Caldilinea, Sporichthya, and Thermomicrobium were higher in fish from the MOD system than the LOW system. Acinetobacter was also more abundant in fish fed the prebiotic diet compared to the basal diet.