Jiasong Zhang

This study evaluated dietary Eleutherine americana water extract (EAW, 0 [NC], 1 [LD], 5 [MD], and 10 [HD] mL/kg) in 480 juvenile leopard coral grouper (Plectropomus leopardus; initial body weight, 11.72 ± 0.34 g) over 8 weeks, with four replicate tanks of 30 fish per treatment. EAW did not significantly improve growth performance, but survival was higher in MD and HD than in NC (p < 0.05). Histological observations indicated more intact mucosal folds, greater crypt depth, and higher goblet-cell counts. Metabolomic analysis showed lower carnitine levels and higher phospholipid and prostaglandin metabolites, with annotated differences in bile acid biosynthesis, amino acid metabolism, and carbon metabolism pathways. Intestinal microbiota profiles showed lower relative abundances of Pseudomonadota and Basidiomycota in EAW groups, lower Actinomycetota in LD and MD, and higher Bacteroidota and Bacillota in MD. At the genus level, Bradyrhizobium, Microbacterium, and Sphingobium abundances were lower, and Afipia abundance was higher, in EAW groups. Functional profiles varied in carbohydrate, amino acid, and lipid metabolism categories. Microbiota–metabolite correlation networks identified Pseudomonadota, Actinomycetota, hexosylceramides, and carnitines as highly connected features. Network pharmacology identified pdgfra, pdgfrb, and sirt1 as candidate targets of the major EAW components eleutherol, eleutherin, and isoeleutherin. The survival and intestinal findings support further evaluation of EAW as a feed additive for intestinal health in leopard coral grouper.

Litsea citrata essential oil (LC-EO) has been proposed as a potential natural additive for mitigating heat stress in aquaculture species. This study evaluated the association between LC-EO exposure, survival performance, and transcriptomic responses of Artemia franciscana under normal (28°C) and heat-stress (34°C) conditions. Supplementation with 0.005% LC-EO was associated with significantly improved survival under heat stress. Transcriptomic analysis identified 318 differentially expressed genes (DEGs) under normal conditions and 764 DEGs under heat stress. Functional enrichment analyses indicated that LC-EO exposure was associated with altered expression of genes involved in detoxification, antioxidant-related processes, immune regulation, nucleotide metabolism, and cellular maintenance, with enriched pathways including lysosome, glutathione metabolism, cytochrome P450, purine and pyrimidine metabolism, and RNA polymerase. Quantitative RT-PCR validation of eight selected DEGs showed strong concordance with RNA-Seq data (R = 0.83–0.94, P < 0.001), supporting the reliability of the transcriptomic dataset. Collectively, these results suggest that LC-EO exposure is associated with transcriptional modulation of stress-responsive pathways under heat stress, generating testable hypotheses regarding its potential role in enhancing thermal tolerance in A. franciscana . Functional validation will be required to determine whether these transcriptomic changes translate into causal physiological protection.

Nitrite is a common toxic substance in aquaculture, and microplastics are environmental pollutants capable of adsorbing small molecules/particles. Shrimp rely mainly on the hepatopancreas to accomplish detoxification metabolism. In this study, we investigated the individual and combined effects of nitrite and microplastics on the physiological function of the P. vannamei hepatopancreas. The results demonstrated that both nitrite and microplastics induced morphological damage, with the combined stress exacerbating tissue damage. Oxidative stress biochemical indicators were disrupted, and most enzyme activities and gene expression levels were upregulated to varying degrees in each experimental group. The expression levels of immune genes (cytC, CASP-3, Crus, ALF, and proPO), detoxification metabolism genes (CYP450, EH1, SULT, and UGT), and oxidative-stress-related genes (ROMO1, SOD, GPx, and Trx) exhibited different fluctuations. Nitrite and microplastic stress resulted in altered hepatopancreatic function, mainly involving amino acid biosynthesis and metabolism, ABC transporters, oxidative phosphorylation, and the mTOR pathway. We identified 17 metabolic biomarkers, including 6 lipids (Oleic acid, Prostaglandin G2, Linoleic acid, Palmitic acid, Docosahexaenoic acid, Docosapentaenoic acid), 6 amino acids (L-Leucine, Agmatine, L-Arginine, L-Tyrosine, Ornithine, N-Acetylornithine), and 5 carbohydrates (Glyceric acid, Citric acid, D-Mannose, Sorbitol, Fumaric acid). These findings suggest that nitrite and microplastic stresses cause hepatopancreatic tissue damage and induce oxidative stress, physiological and metabolic dysfunction in the shrimp P. vannamei, thereby impacting its normal physiological functions.

The intestinal microbiota is a complex and dynamic community that contributes to digestion and plays a crucial role in regulating immune health. In this study, post-metamorphic bullfrogs ( Aquarana catesbeiana ) at different ages (1, 2, 3, and 4 months) were investigated. Growth performance assessment, intestinal histomorphological analysis, and 16S rRNA sequencing were employed to systematically examine the dynamics and diversity of microbial communities in the small intestinal segments (duodenum, jejunum, and ileum). Results showed that bullfrog growth indices increased with age, with faster body weight gain during 2–3 months; notably, this was significantly positively correlated with intestinal morphological development (villus height and muscle layer thickness) ( p < 0.05). In terms of microbial composition, Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria were dominant phyla, while different intestinal segments harbored specific dominant genera. Among them, Cetobacterium was consistently detected throughout the growth period, suggesting it is likely the core symbiont in bullfrog intestines. Moreover, microbiota function varied with growth stages: at 1–2 months, Bifidobacterium and Cetobacterium synergistically participated in immune regulation and basic metabolism, whereas at 3–4 months, Weissella , Lactococcus , and Bacteroides became dominant, with their functions shifting toward efficient energy conversion. Additionally, Alpha diversity analysis showed a decreasing trend in the Simpson index with development, while Beta diversity analysis revealed that microbiota composition was similar among different intestinal segments at the same age but that significant differences existed in each segment during 2–3 months. Overall, this study reveals the specific distribution characteristics of probiotic microbiota in bullfrogs at different growth stages, thereby providing a scientific basis for screening growth-promoting frog-derived probiotics that match host physiological traits.

Global freshwater scarcity necessitates the exploitation of alternative water resources for aquaculture. Chloride-type saline-alkaline water, characterized by high salinity but moderate pH, is widely distributed in arid regions worldwide and represents a vast, underutilized resource. This study comprehensively evaluated the potential of the endemic Ili perch (Perca schrenkii) for aquaculture in such environments. Through acute stress experiments, we determined its 96 h median lethal salinity (LC₅₀) to be 12.396 ppt, with a safe concentration of 3.72 ppt. Physiological analysis revealed a critical salinity threshold of 13 ppt, beyond which osmoregulatory collapse (indicated by plasma Na⁺/K⁺ dysregulation and Na⁺-K⁺-ATPase suppression), oxidative damage (elevated malondialdehyde), and immune suppression occurred. In contrast, chronic 60-day exposure to salinities up to 7 ppt demonstrated successful long-term acclimation. Acclimated fish re-established ion homeostasis, as plasma ion levels normalized, and exhibited sustained antioxidant enzyme (SOD, CAT) and immune parameter (AKP, ACP, IgM) activities without signs of damage. Our findings establish P. schrenkii as a highly promising species for chloride-type saline-alkaline aquaculture. The study provides a physiological framework for its adaptation and offers evidence-based salinity guidelines for its sustainable cultivation, thereby contributing to the expansion of aquaculture into non-traditional water resources.

The escalating scarcity of freshwater resources necessitates the utilization of alternative saline waters for sustainable aquaculture. Perca schrenkii, an endemic fish from the Ili River basin, demonstrates considerable potential for cultivation in chloride-type saline–alkaline waters: its 96 h acute salinity tolerance is higher than that of freshwater populations of its congeneric Perca fluviatilis. This study systematically investigated the histomorphological responses of its key osmoregulatory and metabolic organs—gill, kidney, intestine, and liver—under acute (12–14 ppt for 96 h) and chronic (3–7 ppt for 60 days) salinity stress. Acute exposure induced dose- and time-dependent structural damage, including lamellar fusion in gills, glomerular reduction in kidneys, mucosal atrophy in intestines, and hepatocellular swelling. In contrast, chronic acclimation revealed active remodeling, such as lamellar shortening, renal tubular dilation, intestinal muscularis thickening, and biphasic hepatocyte adjustments. A hierarchical framework of structural adaptation was proposed, delineating Safe (≤3 ppt), Acclimation (5 ppt), Tolerance (7 ppt), and Lethal (≥13 ppt) zones. These findings elucidate the structural basis of salinity tolerance in Perca schrenkii and provide practical morphological indicators for assessing fish health in saline aquaculture.

The American bullfrog (Aquarana catesbeiana), recognized for its aquaculture potential, presents a significant opportunity for sustainable and economically viable production. As the world's leading producer, China plays a pivotal role in the bullfrog industry yet lacks a comprehensive synthesis of its production advancements and challenges. This study addresses this gap by analyzing research and production data from 2020 to 2024, sourced from databases such as Web of Science, Google Scholar, and Scopus. A review of 193 articles across nine thematic areas—including biology, nutrition, aquaculture systems, and disease management—underscores the growing use of bullfrogs as model organisms while addressing ecological impacts and disease concerns. In 2023, China's bullfrog industry achieved a production volume exceeding 1 million tons, valued at 100 billion CNY (15.26 billion USD). However, challenges such as inconsistent production standards and wastewater‐induced environmental pollution remain unresolved. Through an evaluation of various farming models, this study identifies the concept of industrial parks utilizing greenhouses with recirculating aquaculture systems (RAS) as a highly promising strategy for improving food safety and promoting environmental sustainability. The findings emphasize the need for targeted improvements in farming practices and regulatory frameworks to ensure sustainable growth. As a strategic initiative, we propose establishing industrial parks dedicated to bullfrog farming, aligning economic development with environmental goals, and positioning the industry for long‐term global competitiveness.

Bullfrogs (Aquarana catesbeiana) are increasingly cultivated for their high nutritional value and adaptability to intensive aquaculture systems. However, ensuring optimal intestinal health and growth performance remains a challenge due to poor water quality and high stocking densities. This study evaluated the effects of varying dietary concentrations of citral, a natural compound from lemongrass essential oil, on the intestinal health, microbiota, antioxidant capacity, and growth performance of juvenile bullfrogs. A total of 200 juvenile bullfrogs (initial weight 6.85 ± 0.71 g) were randomly assigned into six groups, each receiving diets supplemented with citral at 0, 1, 2, 4, 8, and 16 mL/kg feed for 8 weeks. Citral supplementation significantly improved intestinal morphology, with goblet cell numbers, mucosal thickness, and villus-to-crypt ratios peaking at 2–4 mL/kg (P < 0.05). Optimal doses of 2–4 mL/kg also enhanced digestive enzyme activities, with α-amylase, lipase, and pepsin activities showing significant increases compared to the control group (P < 0.05). Antioxidant markers, including total antioxidant capacity (T-AOC) and glutathione (GSH), were highest at 2 mL/kg, while higher citral concentrations reduced superoxide dismutase (SOD) and catalase (CAT) activities, indicating potential oxidative stress at 8–16 mL/kg (P < 0.05). Citral also modulated the intestinal microbiota, increasing the relative abundance of beneficial bacteria such as Cetobacterium at 1–2 mL/kg (P < 0.05). However, microbial diversity decreased significantly at concentrations above 4 mL/kg. Growth performance analysis revealed that 4 mL/kg citral supplementation significantly improved weight gain rate (WGR), specific growth rate (SGR), carcass weight (CW), and feed efficiency (FE), while survival rates declined at 16 mL/kg (P < 0.05). A linear regression model determined the optimal dietary citral concentration to be 3.216–3.942 mL/kg. This study concludes that dietary citral at 2–4 mL/kg optimally enhances growth performance, intestinal health, and antioxidant capacity in juvenile bullfrogs, while higher concentrations may disrupt gut health and oxidative balance. These findings provide valuable insights into the use of natural compounds like citral for sustainable aquaculture practices.

Bullfrogs (Aquarana catesbeiana) are increasingly farmed for their high nutritional value and adaptability to intensive aquaculture systems. However, salinity stress due to environmental changes and habitat salinization poses a significant challenge for both wild and farmed bullfrogs. This study examines the physiological responses of juvenile bullfrogs to varying salinity levels (0, 2, 4, 6 ppt) to better understand their capacity for osmoregulation and adaptation to salinization. Juvenile bullfrogs underwent salinity treatments for one week, and various physiological parameters, including digestive enzyme activity, antioxidant enzyme activity, and serum biochemical indicators, were measured. The study revealed that moderate salinity (2–4 ppt) enhanced pepsin and amylase activity while maintaining high survival rates. However, higher salinity levels (6 ppt) impaired antioxidant defense mechanisms and liver tissue, increasing oxidative stress markers such as malondialdehyde (MDA). The results suggest that bullfrogs possess a degree of salt tolerance, which may predict their resilience to future landscape salinization driven by environmental changes. This research provides valuable insights into the osmoregulatory mechanisms of amphibians under salinity stress, addressing a critical gap in knowledge essential for both conservation and aquaculture management.

Introduction: The use of plant essential oils as anesthetics for fish has gained increasing attention, but ethanol, often used as a co-solvent, presents certain limitations. Recently, Magnolia denudata essential oil (MDO) has emerged as a promising alternative for fish anesthesia and sedation.Methods and results: To further improve MDO anesthesia efficacy, this study developed nanoemulsion (NE) and self-microemulsifying drug delivery system (SMEDDS) formulations of MDO. Transmission electron microscopy and stability tests confirmed that both NE and SMEDDS possess smaller particle sizes and are stable under various temperature conditions. Anesthetic trials on fish demonstrated that these formulations reduced the time needed to induce anesthesia compared with the non-formulations. Additionally, physiological assessments of the fish gills showed that neither NE nor SMEDDS caused irreversible damage to respiratory function.Discussion: Overall, NE and SMEDDS present a safe and effective delivery system for MDO, enhancing its anesthetic properties while minimizing potential harm to aquatic organisms compared to traditional methods.