Effects of fish meal replacement with meal on growth performance, pigmentation, and liver health of largemouth bass ().

meal is a potential protein source for aquafeeds. However, the physiological response of carnivorous fish fed meal remains elusive. This study evaluated the effects of replacing dietary fish meal with meal on growth performance, pigmentation, and liver health in largemouth bass. Five diets were formulated to replace dietary fish meal of 0% (C0, control), 25% (C25), 50% (C50), 75% (C75), and 100% (C100) with meal, respectively. Total 300 fish (17.6 ± 0.03 g) were randomly assigned to 15 tanks (3 tanks/group). Fish were fed the experimental diet twice daily for 8 weeks. The increased dietary meal quadratically influenced the final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), and feed intake (FI), which were significantly lower in the C100 group than in the other groups ( < 0.05). The feed conversion ratio (FCR) increased linearly or quadratically with dietary meal. Dietary meal linearly or quadratically increased the lutein content of plasma, liver, and dorsal muscle of largemouth bass ( < 0.05). Compared to the C0 group, all supplemented meal groups significantly improved the yellowness (b∗) of the dorsal body (1.5 to 2.0 fold), abdominal body (1.5 to 1.8 fold), and dorsal muscle (3.8 to 5.4 fold) of largemouth bass ( < 0.05). In addition, compared to the C0 group, the liver vacuolation area of fish was significantly increased in the C75 and C100 groups ( < 0.05). Transcriptional levels of apoptosis-related genes of β-cell lymphoma-2 () caspase-9-like () and caspase-3a () were markedly upregulated (0.9 to 1.6 fold) in the C100 group compared to the C0 group ( < 0.05). Based on the quadratic regression analysis between FBW, WGR, or SGR and dietary meal level, largemouth bass had the best growth when replacing 31.7% to 32.6% of fish meal with 15.03% to 15.43% dietary meal. The present results indicated that dietary supplementation with meal (11.85% to 47.45%) significantly enhanced the pigmentation; however, total replacement of fish meal (40%) with meal (47.45%) caused growth retardation, apoptosis, and liver damage in largemouth bass.