In recent decades, the demand for aquatic products has been continuously increasing, the global fisheries and aquaculture production has grown at an unprecedented rate, and fish is an ideal source of high-quality protein and micronutrients for humans [1]. High-density aquaculture has exposed fish to significant environmental stress, leading to compromised disease resistance and heightened vulnerability to various pathogens [2]. Various bacterial pathogens have severely restricted the fish industry, resulting in an increase in morbidity and mortality [3]. A. hydrophila (Aeromonas hydrophila), a gram-negative facultative anaerobic bacterium, widely present in natural ecosystems [4], mainly distributed in rivers and tap water, which can cause aquatic animals several symptoms such as intussusception, enteritis, and sepsis [5]. Currently, antibiotics and other drugs are employed to prevent bacterial infections in aquaculture [6]. The indiscriminate use of antibiotics not only leads to the development of resistance among pathogenic bacteria but also contributes to environmental pollution and the antibiotic residues in fish [7], which poses potential risks to human health and the aquatic environment [8]. It is critically important to identify effective alternatives to antibiotics that can enhance the immunity and disease resistance of aquaculture species.

In the past decades, various compounds such as grape seed [9], cornelian cherry [10], oregano essential oil [11], Lactobacillus fermentum and ferulic acid [12] have been found to be incorporated into diets to enhance the ability of aquatic animals to resist external stress during their survival. According to recent reports sulforaphane (SFN) has been demonstrated to stimulate the production of antioxidant enzymes in the liver, facilitates the removal of reactive oxygen species (ROS), thereby enhancing cellular defense mechanisms [13]. The case reported here illustrates that SFN engages with mediators involved in other critical inflammatory signaling pathways, including inhibition of nuclear factor‐κB (NF-κB) and inflammasome complexes [14]. Research indicates that the concurrent use of SFN offers a protective benefit against liver damage caused by sodium valproate in rats, as evidenced by a reduction in malondialdehyde (MDA) and tumor necrosis factor-α (TNF-α) levels, alongside an increase in heme-oxygenase (HO)-1 concentration [15]. Also, the previous results have shown that dietary supplementation of SFN could beneficially attenuate the oxidative stress, alter­ations in the liver functions[16,17]. Recently, several studies have shown that SFN could attenuate High-Fat Diet (HFD)-induced and BPA-induced lipid synthesis and catabolism disorder, and lipid accumulation in the liver [18,19]. Regarding the application of SFN in aquatic animals, it has been shown to enhance the stimulation ability of Litopenaeus vannamei in response to ammonia nitrogen [20]. SFN has been shown to mitigate the oxidative stress caused by oxidized fish oil in Litopenaeus vannamei [16]. Recently, several studies have shown that SFN could attenuate HFD-induced and BPA-induced lipid synthesis and catabolism disorder, and lipid accumulation in the liver [18,19]. To date, the information regarding SFN on liver lipid metabolism against A. hydrophila infection in fish is limited, with few studies exploring this area.

C. carpio (Cyprinus carpio) is commonly found in freshwater systems and is cultivated in numerous countries, highlighting its ecological significance and suitability as an ideal organism for research studies [21]. In the current research, RNA-seq methodology was utilized to analyze the liver of C. carpio infected by A. hydrophila, aiming to confirm the roles of crucial genes related to immune regulation, antioxidant functions, and lipid metabolism. This approach provides a scientific foundation for elucidating the lipid metabolic disorders of C. carpio to A. hydrophila.