Background: Chinese soft-shell turtle (Pelodiscus sinensis) is an important commercial species for their high nutritional value and unique taste, but it has been a vulnerable species due to habitat loss. In this study, homologous juvenile turtles were allocated to lake, pond and paddy field to investigate the habitat effects on turtles. Results: The growth, morphology and gut microbial communities were monitored during the 4 months cultural period. It showed higher growth rate of turtles in paddy field and pond. The appearance, visceral coefficients, gut morphology and microbial communities in turtles were distinct among different habitats. The microbial community richness on Chao1 was obviously lower in initial turtle guts from greenhouses, whereas it was relative higher in turtle guts sampled from paddy fields than ponds and lake. Significant differences on dominant microbes were found among initial and subsequent samples from different habitats. Firmicutes was the most abundant phylum in the guts of turtles sampled from the greenhouse initially, while Proteobacteria was the most abundant phylum after cultivation in different habitats, followed by Bacteroidetes. The microbial composition were distinct in different habitats at 60d, and the appearance of dominant phyla and genera was more driven by sampling time than habitats at 120d. Both the sampling time and habitats affected the appearance of dominant phyla and genera during the cultivation. The functional predictions indicated that both habitat type and sampling time had significant effects on metabolic pathways, especially amino acid and carbohydrate metabolism. Conclusions: The turtles could adapt to natural lakes, artificial ponds and paddy fields. The gut microbial abundance was different among the habitats and sampling time. The species of microbes were significantly more diverse in paddy field specimens than in those from ponds and lakes. Rice-turtle coculture is a potential ecological and economic farming mode that plays important roles in wild turtle protection and food security.

Sustainable development of the largemouth bass industry is hindered by limited freshwater resources. Consequently, the expansion of farming space by brackish and saline water aquaculture has become imperative. Largemouth bass is an economically important freshwater fish species. However, there is presently a lack of germplasm resources with the capacity to adapt to hypertonic environments and maintain rapid growth. A genome-wide association study is a technique used for the detection of genetic variants associated with specific phenotypic traits. In this study, we firstly applied this technique to explore the potential single-nucleotide polymorphism (SNP) locus and candidate genes associated with rapid growth and adaptation to the hypertonic environment of largemouth bass. A total of 10 potential growth-related SNPs were obtained on chromosome 16, and SNP16:4120214 was a significant SNP peak. Based on these SNPs, 23 candidate genes were annotated in the genome, including Nkcc1, Mapkap1, Hmgcs1, Slc27a6, and Shroom3. Shroom3 expression was significantly higher in individuals enriched for the most growth-advantageous genotypes. Shroom3 upregulation is beneficial for fish growth in hyperosmotic environments. This study provides insight into the genetic basis of rapid growth in hypertonic environments and foundational information for the future breeding of salt-tolerant largemouth bass.

The Chinese soft-shelled turtle (Pelodiscus sinensis) is an important freshwater aquaculture turtle due to its taste and nutritional and medicinal value. More ecological culturing modes, such as rice–turtle co-culture, should be developed to meet the ecological benefit demand. We compared growth, physiological parameters, and transcriptome data to detect the physiological responses and regulatory mechanisms of pond-cultured turtles as compared to co-cultured turtles. The co-cultured turtles grew slower than pond-cultured turtles. The gonadosomatic index of co-cultured male turtles was lower than that of pond-cultured male turtles, and both the mesenteric fat index and limb fat index were lower in co-cultured turtles than in pond-cultured turtles (p < 0.05). The blood GLU of the co-cultured turtles was significantly lower than the GLU of the pond-cultured turtles (p < 0.05), while the values of CRE, UA, BUN, AKP, ACP, GOT, and CAT were higher in the co-cultured turtles than in the pond-cultured turtles (p < 0.05). In total, 246 and 598 differentially expressed genes (DEGs) were identified in the brain and gut from turtles cultured in the two different modes, respectively. More DEGs were related to environmental information processing, metabolism, and human diseases. In the brain, the top enriched pathways of DEGs included the longevity regulating pathway, glycerolipid metabolism, cytokine–cytokine receptor interaction, Toll-like receptor signaling pathway, and PI3K-Akt signaling pathway, while in the gut, the top enriched pathways of DEGs included the cell cycle, DNA replication, cellular senescence, and p53 signaling pathway. The turtles acclimated to the different culturing conditions by adjusting their growth, physiological, and biochemical characteristics and related gene expression during a short culture period.

The color of crayfish (Procambarus clarkii) shells not only affects their value, but also has a significant impact on individual size. Astaxanthin is a common carotenoid that has been found in many studies to have different functions, including regulating body color formation. In this study, the levels of different carotenoids were detected using high performance liquid chromatography (HPLC) and found a significant correlation between astaxanthin content and shell color. An astaxanthin gene (PcASTA) was identified from P. clarkii, and it was expressed in tissues of crayfish with dark-red shells and green shells. The highest expression levels of PcASTA were found in the hepatopancreas, followed by the muscle. The expression of PcASTA in all tissues of red shell crayfish was higher than that of green shell crayfish, indicating that PcASTA may be involved in shell color formation in crayfish. Moreover, high water temperature and feeding β-carotene can lead to an increase in tissue expression of PcASTA and astaxanthin content in crayfish shells. The findings indicate that PcASTA may affect shell color in P. clarkii by being involved in astaxanthin synthesis and transformation.

Feeding inefficiencies in pond aquaculture not only elevate operational costs and environmental impact but also compromise fish growth and welfare, driving an urgent need for precision feeding technologies. However, accurate, real-time detection of feeding events in complex, cluttered pond environments remains challenging due to dense, small targets, variable lighting, and background disturbances. To address these issues, we propose PM-YOLO, an enhanced YOLOv8n framework that integrates Parallelized Patch-Aware Attention modules for multi-scale feature retention and a Minimum Point Distance IoU loss term for superior bounding-box regression of overlapping fish. We also curate FeedFishDatas, a 7,400-image dataset capturing diverse feeding scenarios, and demonstrate that PM-YOLO achieves 87.7% precision and 83.5% mAP-50—outperforming standard YOLOv8n and YOLOv11n—while maintaining real-time inference at 8.1 ms per frame. Our ablation studies isolate the contributions of each innovation, confirming their synergistic impact on detection performance. Looking ahead, we envisage lightweight PM-YOLO variants via model pruning and quantization for edge deployment, temporal smoothing for stability, and domain adaptation to extend applicability across species and water conditions, paving the way for fully automated, closed-loop feeding systems in sustainable aquaculture.

This study presents the development of a quantitative evaluation method utilizing machine vision technology to characterize the extent of body surface damage in largemouth bass (Micropterus salmoides) infected with largemouth bass ranavirus (LMBV). High-resolution, multi-angle images (6000 × 4000 pixels) of the body surface from 239 infected specimens were acquired at a fixed distance of 40 cm using a SONY ILCE-7RM3 digital camera within a GODOX-LST60 softbox. Key parameters, including the number of segmented injury areas, the count of body surface lesions, and the total lesion area, were analyzed. These parameters were integrated through principal component analysis (PCA) to construct a comprehensive damage scoring model. The severity of viral-induced body surface damage was categorized into four grades: uninjured (0), minor injury (1), moderate injury (2), and severe injury (3). Histopathological examination revealed that early-stage infection (grade 1) predominantly exhibited localized hemorrhagic spots in the muscular region of the body side (B/E region) with limited lesion area. In contrast, moderate to severe infections (grades 2–3) were characterized by extensive ulceration, muscle necrosis, and visceral lesions, including hepatic fibrosis and splenic granulomatous formations. Quantitative real-time PCR (qRT-PCR) analysis demonstrated a progressive upregulation of pro-inflammatory cytokines (IL-6, IL-8, TNF-α, CXCL2) in immune organs, concomitant with increased expression of apoptosis-related genes (CASP8, CYC). This study successfully established a rapid and objective quantitative grading system for ranavirus infection, offering a novel technical approach for early diagnosis and precise prevention and control strategies against largemouth bass ranavirus.