Aquatic food is becoming an important food source that provides
micronutrients to human beings. The decline of wild aquatic animals makes aquaculture become increasingly important to play this role. However,
infectious diseases, especially
bacterial infection, represent severe threat to aquaculture, which causes huge economic loss. Meanwhile, strategies in managing
bacterial infection in an
antibiotic-independent way are still lacking. In this study, we monitor the metabolomic shift of crucian carp upon Aeromonas hydrophila
infection. We find that the metabolism of the fish that died of
infection is distinct from the ones that survived. By multivariate analysis, we identify
fructose as a crucial
biomarker whose abundance is significantly different from the dying and surviving groups where the surviving group has a higher content of
fructose than the dying group. Exogenous supplementation of
fructose increases fish survival rate by 27.2%. Quantitative gene expression analysis demonstrated that
fructose enhances the expression of
lysozyme and
complement 3 expression, which is also confirmed in the serum level. Furthermore, the augmented
lysozyme and C3 levels enhance serum cell lytic activity which contribute to the reduced bacterial load in vivo. Thus, our study demonstrates a metabolism-based approach to manage
bacterial infection through modulating immune response to clear
bacterial infection.