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Fish are poikilothermic vertebrates and their physiological activities are affected by water temperature. In recent years, extreme weather has occurred frequently, and temperature changes have adversely affected the growth of farmed fish. To explore the changes in gill tissue structure caused by changing the water temperature and the relationship between the intestinal microbiota and the Leiocassis longirostris host adaptation mechanism, gill tissue sections and intestinal microbial 16S rRNA amplicon sequencing were conducted under different temperature stress (low temperature 4 °C, normal temperature 26 °C and high temperature 32 °C). The results showed that heat stress and cold stress caused injury and swelling, terminal congestion, cell vacuolation, and necrosis of the gill tissue of L. longirostris . For intestinal microbiota, the abundances of Pseudomonadota and Bacillota increased at the cold stress, while the abundances of Fusobacteriota and Bacteroidota increased at the heat stress. The number of opportunistic bacteria, mainly Aeromonas and Acinetobacter , was the highest under cold stress. In addition, the richness of the intestinal microbiota decreased significantly at heat and cold stresses, while evenness increased. Prediction of intestinal microbiota function showed that most common functions, such as metabolism of cofactors and vitamins, energy metabolism and replication and repair, were decreased significantly at heat stress and cold stress, and phylogenetic relationship analysis revealed significant differences among the groups. In conclusion, the change of temperature altered the gill tissue structure, and affected the structure and homeostasis of the intestinal microbiota, thus affecting the survival time of L. longirostris , and cold stress had a greater effect than heat stress.

Body color is the most prominent phenotypic trait in animals. To investigate the molecular regulatory mechanisms underlying skin pigmentation and body color in Channa argus, single-nucleus RNA sequencing technology was employed to analyze cell diversity and functional changes in the skin of normal and albino C. argus. Three pigment-related cell types, seven immune-related cell types, and nine other skin-related structural and functional cell types were identified. The skin of albino C. argus, which appears white to the naked eye, contains numerous melanocytes and iridophores with reflective silver properties. Compared to normal C. argus, melanocytes in albino individuals contained fewer melanin granules, while iridophores exhibited increased chromogenic substances. Melanocyte-specific genes—kitlg, myo5a, and scarb1—were significantly downregulated in albino melanocytes (p < 0.05). Conversely, iridophore-specific genes alk, pnp, and gpnmb were significantly upregulated in albino skin, whereas mlph was significantly downregulated (p < 0.05). Weighted gene co-expression network analysis revealed that scarb1 was associated with the melanocyte module, alk was identified as a core gene, and pnp was linked to the iridophore module. Functionally, scarb1 is involved in pigment transport, pnp in purine synthesis, and alk is essential for iridophore development. Therefore, scarb1, pnp, and alk may be correlated to albinism in C. argus. Overall, this study constructed a single-cell transcriptional atlas of C. argus skin, providing valuable reference data for further research into the regulatory mechanisms governing body color formation and maintenance in this species.

The photovoltaic (PV) fishery breeding model integrates the generation of solar energy with aquaculture, yet its impacts on aquatic organisms remain poorly understood. This study investigated how PV panel shading affects the intestinal microbial ecosystem of Litopenaeus vannamei . We conducted a controlled 80-day experiment comparing shrimp reared under PV panels (ZG group) versus those reared in traditional open ponds (CK group), with quadruplicate 800 m² ponds per group under standardized conditions (80 shrimp/m², salinity 15–18‰). High-throughput 16 S rRNA sequencing was employed to analyze microbial composition, diversity, and predicted functional profiles. The growth data were collected daily during the initial 20-day period and subsequently at five-day intervals thereafter. The results demonstrate that the ZG group exhibited significantly reduced body length compared to the CK group after 20 days of culture ( P  < 0.05), while body weight was significantly lower after 16 days ( P  < 0.05).‌ The results of the intestinal microbiota analysis showed that Proteobacteria and Firmicutes were the main components of the intestinal microbiota in the CK and ZG groups, while Oceanobacillus and Candidatus_Electronema were present as indicator species in the CK and ZG groups, respectively. Analysis of the Chao1 index and Shannon index revealed no significant differences in either the diversity or evenness of the intestinal microbiota of L. vannamei among the experimental groups. In addition, significant differences between the groups were detected by the β -diversity analysis. A predicted bacterial function analysis also revealed significant differences in functional abundance between the two groups. This study provides critical insight into how PV shading alters shrimp microbiota and growth performance, offering practical guidance for optimizing sustainable PV-aquaculture integrated systems.

Intestinal microorganisms that living in the mucosa and contents of the gastrointestinal tract of animals, have close links with their hosts over a long evolutionary history. The community structure of the fish intestinal microbiota is associated with food, living environment, and the growth stage. To screen for potential probiotics that can be used for regulating breeding behaviors, this study focused on the diversity of fish intestinal microorganisms. This study aimed to investigate the effects of sex and body weight on the intestinal microbial diversity of Gymnocypris chilianensis in the wild. The results showed that the significant high diversity and richness of intestinal microbiota were fould in heavier individuals, and males. The dominant bacterial phyla of G. chilianensis were Proteobacteria, Firmicutes, and Bacteroidetes. In addition, the abundance of Firmicutes varied significantly among different body weights. The genus profile revealed that small individuals were dominated by Weissella , while females were dominated by Aeromonas , and both large individuals and males were dominated by other genera. Phylogenetic relationships and UPGMA clustering analysis showed significant differences among the groups. In general, the two main factors that have an effect on the intestinal microbiota diversity of wild G. chilianensis are sex and body weight.

Triplophysa siluroides, a unique species of plateau fish, holds significant economic value. However, its natural population has sharply declined due to overfishing and the construction of water conservancy projects. Investigating the various conditions necessary for its growth is a crucial prerequisite for successful artificial breeding. This study used Edwardsiella tarda as the pathogenic bacterium to determine the median lethal concentration following infection of T. siluroides, as well as to examine changes in tissues, organs, and gene expression. The study found that dead T. siluroides displayed symptoms such as abdominal distension, fluid accumulation, and a reddened anus, and the median lethal concentration of E. tarda for T. siluroides was calculated to be 1.00 × 106 CFU/mL. Following infection with E. tarda, the liver, intestine, gills, spleen, and kidneys exhibited varying degrees of lesions. Transcriptome sequencing identified a total of 54,667 genes. Compared to the blank control group, 192 genes were downregulated and 125 genes were upregulated in T. siluroides infected with E. tarda. In contrast, after infection with the poly(I:C) viral mimic, 225 genes were downregulated and 436 genes were upregulated. This study determined the median lethal concentration of E. tarda for T. siluroides via intraperitoneal injection under laboratory conditions. The results may contribute to disease prevention and control in the breeding of T. siluroides, as well as inform future risk assessments of infection in aquaculture water bodies.

To study the impact of photovoltaic facilities on the climate of aquaculture areas within the new aquaculture model (photovoltaic fishery mode, PFM), meteorological monitoring instruments were used to measure light intensity, temperature, humidity, and water environment in the PFM aquaculture areas of Dongying City and Taishan City. The experimental results showed that photovoltaic facilities (PFs) significantly affected lighting, causing a substantial decrease in light intensity above the ponds, with an annual average reduction ranging from 24.15% to 67.75%, compared to the traditional pond mode (TPM). The impact of flexible PF on lighting was less pronounced than that of fixed photovoltaic facilities, with decreases of only 24.15% and 65.06%, respectively, compared to TPM. PF influenced temperature within a small range, particularly in the Dongying City aquaculture area, where the temperature difference reached 1.48 °C. The effect of flexible PF on temperature, with a decrease of only 0.071%, was much smaller than that of fixed PF, which showed a decrease of 3.28% compared to TPM. In both Dongying City and Taishan City aquaculture areas, PF reduced environmental humidity by 4.71% to 9.62% compared to TPM. In Dongying City, the water temperature under the PFM-fixed system was 0.39 to 3.78 °C lower than that of TPM. The annual biomass variation patterns of zooplankton and phytoplankton in Dongying City and Taishan City were opposite. This study provides data to support further research on the relationship between PFM and aquaculture.

The transition from live bait (LF) feeding to compound feed (CF) feeding in aquaculture is of great production significance. In recent decades, cultivation with CF has become a focus for practitioners and researchers dealing with Siniperca chuatsi. This study focused on experimental subjects of S. chuatsi fed with CF and LF, using short-distance transportation as a stimulating factor. For the first time, the differences between S. chuatsi fed with CF and LF were analyzed from the perspective of stress response during transportation. This study found that after transportation stimulation, the activities of LZM and the contents of MDA, TGs, and glucose in the brain, liver, kidneys, muscles, stomach, pyloric caecum, intestines, and blood of S. chuatsi fed with CF were higher compared to S. chuatsi fed with LF (p < 0.05). Significant differences were observed in the impacts of various diets on the gastrointestinal tract, particularly in the intestine. In summary, this study found that S. chuatsi fed with CF could retain more energy after transport stimulation and exhibited stronger resistance to microbial stress, but they had a weaker antioxidant capacity. Therefore, in future research on CF for S. chuatsi, we need to focus on its ability to enhance antioxidant capacity.

Cold shock represents a prevalent but harmful environmental stress factor that poses significant threats to fish survival and reproductive success. In fish, the brain acts as a central regulator of thermoregulatory processes. Nevertheless, how different brain regions respond molecularly to cold exposure remains largely unknown. To address this, this study systematically investigated the effects of acute cold stress on five specific brain regions of Leiocassis longirostris using RNA-seq. The findings demonstrated that all five brain regions were significantly impacted by cold treatment, with the mesencephalon (MB) showing the most substantial changes. GO and KEGG enrichment analyses indicated that cold stress disrupted processes including gene expression regulation, circadian rhythms, and immune function within brain tissues. Through Weighted Gene Co-Expression Network Analysis (WGCNA), the MB was identified as the core responsive region, and the brain’s reaction to cold stress was strongly correlated with circadian rhythm, spliceosome, and ubiquitination. In summary, our investigation demonstrates that the MB represents a principal region for cold stress response in L. longirostris, involving alterations in circadian clocks, immune function, and inflammatory responses, alongside suppression of gene expression processes and ubiquitination-mediated proteolysis.

Microbial feed additives can effectively promote the healthy development of aquaculture, and Lactobacillus acidophilus can be utilized to mitigate disease risks and enhance productivity while minimizing antibiotic use. This article summarizes research on the application of L. acidophilus in aquaculture, focusing on growth and nutrient utilization, intestinal structure and microbial communities, disease prevention and control in aquatic organisms, and the regulation of water quality. This review holds significant implications for the development of compound feed additives and environmental regulators involving L. acidophilus, as well as for future aquatic food safety.

Ammonia nitrogen is a common environmental stressor in intensive aquaculture, but the mechanisms by which it causes intestinal mucosal immune failure remain incompletely understood. Using combined and models of along with histology, transepithelial electrical resistance (TEER) measurement, immunofluorescence, transcriptomics and qRT-PCR, we observed that ammonia exposure induced inflammatory cell infiltration in the lamina propria and disruption of the intestinal epithelial barrier. Although transcripts of core tight junction (TJ) components (such as ) were significantly upregulated, their protein assembly at the apical membrane was severely disrupted, as indicated by fragmented TJ ultrastructure and a sharp decline in TEER. We refer to this paradoxical response as \"ineffective transcriptional compensation.\" ZO-1 is a key target of this transcription-function decoupling. Pharmacological stabilization of ZO-1 reduced mucosal inflammatory damage and restored TJ protein localization and barrier function without large-scale transcriptional changes. ZO-1 stabilization also partially restored the extracellular matrix-focal adhesion (ECM-FA) pathway, which contributes to mucosal integrity. The decoupling between mRNA upregulation and protein function is a characteristic feature of ammonia-induced mucosal dysregulation in this species. These results indicate that stabilizing ZO-1 may be a potential strategy to strengthen intestinal mucosal resilience in aquaculture.