To understand the impacts of dietary Glycyrrhiza uralensis on the immune responses of Lates calcarifer, the expression of immune-related genes including crp, c-3, c-4, mtor, mlst-8, eif4e, hsp-70, hsp-90, il-8il-8, il-10, tgfβ1, tnf, ifn-γ1, and mxf in L. calcarifer juveniles was evaluated in this study. Fish were fed experimental diets with G. uralensis levels of 0%, 1%, 3%, and 5% for 56 days. The results showed that dietary G. uralensis could improve the growth and survival of L. calcarifer and regulate the immune-related genes’ expression in L. calcarifer. Dietary G. uralensis significantly upregulated the expression level of crp, mtor, hsp-90, c-3, and c-4 genes in the liver of L. calcarifer, while hsp-70 gene expression was nearly downregulated. It did not upregulate the expression of elf4e and mlst-8 in the 1% and 3% inclusion groups, but it was the exact opposite in the 5% inclusion group. G. uralensis significantly affected the expression of il-8, il-10, tnf, ifn-γ1, mxf, and tgfβ1 in the head kidney of L. calcarifer. G. uralensis upregulated the expression of tnf and tgfβ1 consistently, but ifn-γ1 was at a low expression level. The expression of il-8 and il-10 was upregulated in the 1% group, while it was downregulated in the 5% group. The results from the present study indicate that dietary G. uralensis appeared to improve the immune function of L. calcarifer, and the optimum inclusion level should be between 1–3%.

This study investigates the effect of a sudden change in salinity for 48 h on the digestive enzyme activity of juvenile yellowfin tuna. The treatment included a control salinity of 32‰ in natural seawater and an experimental salinity of 29‰. Acute stress experiments were carried out on 72 juvenile yellowfin tuna (646.52 ± 66.32 g) for 48 h to determine changes in digestive enzyme activity in different intestinal sections over time (0 h, 12 h, 24 h, 48 h). The activities of pepsin, trypsin, α-amylase, lipase, and chymotrypsin in the digestive organs (stomach, foregut, and pyloric ceca) of juvenile yellowfin tuna were measured. Pepsin and pancreatic protease in the experimental group were significantly lower than in the control group (p < 0.05). α-amylase showed a fluctuating trend of decreasing and then increasing, and its activity trend was pyloric ceca > foregut > stomach. The lipase activity of gastric tissues decreased at the beginning and then increased, reaching a minimum at 24 h (2.74 ± 1.99 U·g protein⁻¹). The change of lipase in the pyloric ceca and foregut was increasing and then decreasing. The lipase activity trend was pyloric ceca > foregut > stomach. The chymotrypsin showed a decreasing and increasing trend and then stabilized at 48 h with a pattern of pyloric ceca > foregut > stomach. Similarly, the gut villi morphology was not significantly altered in the acutely salinity-stressed compared to the non-salinity-stressed. This study suggests that salinity may change the digestive function of juvenile yellowfin tuna, thereby affecting fish feeding, growth, and development. On the contrary, yellowfin tuna is highly adapted to 29‰ salinity. However, excessive stress may negatively affect digestive enzyme activity and reduce fish digestibility. This study may provide a scientific basis for a coastal aquaculture water environment for yellowfin tuna farming, which may guide the development and cultivation of aquaculture.

A water environment can impact many physiological processes of aquatic animals. The antioxidant response of immune system of the pearl oyster to temperature and salinity is of great significance to health. This study analyzed the physiological changes and immune responses under different temperature and salinity levels (temperature: 20, 25, and 30 °C; salinity: 23, 28, and 33‰) in the short term (7 d) in the hepatopancreas and other tissues of 405 pearl oysters. The combined effects of temperature and salinity on antioxidants in the immune system of the pearl oyster were evaluated via response surface methodology and Box–Benhnken design (BBD) under laboratory conditions. The secondary effects of salinity on the activities of glutathione peroxidase (GSH-PX), catalase (CAT), and superoxide dismutase (SOD) were significant, and CAT and SOD showed an inverted U-shaped trend with the increase in salinity. Temperature significantly impacted GSH-PX, CAT, glutathione (GSH), and SOD in primary and secondary effects, and the maximum values of CAT, GSH, and SOD were observed. The phenoloxidase (POX) and alkaline phosphatase (AKP) activities increased with the increasing temperatures. The interaction of temperature and salinity was significant on CAT and SOD, but was not significant on GSH-PX. The interaction between salinity and temperature on AKP was significant, which was contrary to the results of AKP in the hemolymph. The expression levels of antioxidant genes varied between tissues, and the expression levels of different genes in the same tissue were different. Appropriate immunity and antioxidant index models were established under the combined temperature and salinity conditions. The optimal combination of temperature and salinity was 24.95 °C and 28.11‰, respectively, and the desirability was 0.803. This study provides theoretical reference points for the pearl oyster to respond to temperature and salinity changes and can be used to establish an index model for shellfish aquaculture.

This study was conducted to determine whether curcumin has a positive effect in greater amberjack (Seriola dumerili), especially the ammonia nitrogen stress tolerance ability. The results showed that the stress recovery process of digestive enzymes amylase and trypsin, as well as absorptive enzymes Na⁺/K⁺-ATPase, γ-GT and CK, was accelerated. Lysozyme activity increased in the fish fortified with both curcumin diets. Aspartate aminotransferase activity restriction was activated at a low curcumin level. However, alanine aminotransferase activity restriction happened only at 0.02% dietary curcumin. Facilitation of lipid metabolism by curcumin was very clear, as triglyceride and total cholesterol content was basically maintained at the original level or even showed a slight decrease after recovery. HSP70 and HSP90 genes were not evidently stimulated to express in liver, kidney and spleen tissues. In addition, curcumin showed its inhibition capacity on IL1β and IFN-γ and a promoting effect on TGF-β1. The expression of NF-κB1 decreased in a higher degree in fish fed with 0.02% dietary curcumin, while 0.01% dietary curcumin accelerated the recovery pace of C3 and lgT after stress. This study showed that dietary curcumin supplementation can enhance ammonia nitrogen stress tolerance in greater amberjack, and its application prospect can be confirmed.

Yellowfin tuna (Thunnus albacares) is a fast-growing, economically valuable pelagic species with increasing potential for aquaculture. However, its high metabolic demands and sensitivity to environmental fluctuations pose significant challenges for closed-cycle cultivation. This review synthesizes a series of recent studies conducted by our research team on the physiological responses and of juvenile yellowfin tuna under key aquaculture-relevant stressors, including thermal fluctuation, hyposalinity, ammonia nitrogen accumulation, and seawater acidification. We detail the mechanisms of oxidative stress, immunometabolic dysfunction, and osmoregulatory disruption across stress conditions, highlighting tissue-specific antioxidant responses, enzyme activity modulation, and microbiota remodeling. Collectively, these physiological responses underscore both the adaptability and vulnerability of yellowfin tuna juveniles in dynamic aquaculture environments. The insights gained from this integrative assessment provide a scientific foundation for optimizing environmental management, nutritional strategies, and system design in yellowfin tuna aquaculture. By aligning culture conditions with the physiological capacities of the species, these findings contribute to improving health, performance, and the long-term sustainability of yellowfin tuna farming operations.

This study investigated the tolerance of juvenile yellowfin tuna (Thunnus albacares) to acute acidification by determining the activities of trypsin, pepsin, α-amylase (AMS), lipase (LPS), lactate dehydrogenase (LDH), pyruvate kinase (PK), and Na+K+-ATPase (NKA) under varying pH conditions, combined with histological section preparation to examine morphological changes. The research aims to provide fundamental reference data for the cage aquaculture of this species. The main findings were as follows: Protease activity increased at pH 7.6; α-amylase activity elevated in the pyloric caeca and liver at pH 7.1, while both α-amylase and lipase activities increased in the stomach at pH 6.6. Foregut enzyme activities decreased with increasing acidity. Hepatic alanine aminotransferase and aspartate aminotransferase were significantly elevated at pH 7.6, whereas gill metabolic enzymes peaked at pH 6.6. Histological analyses showed shortened bends in the midgut villi visible to the naked eye and gill lamellae hyperplasia under low pH conditions. These results indicate moderate adaptability at pH 7.6 but marked physiological stress at pH 6.6.