This study aimed to investigate the response mechanisms of liver and gill tissues in mandarin fish (Siniperca chuatsi) at the histological, apoptotic, and gene expression levels during the weaning process from live prey to artificial feed. By analyzing fish samples at different domestication stages (D0, D7, D14), the results revealed that: (1) Histologically, the gill filaments exhibited shortening and thickening post-domestication, while the liver showed increased vacuolation; (2) apoptosis detection (TUNEL assay) and analysis of apoptosis-related gene (Bax/Bcl-2) expression indicated that the gill tissue experienced a significant increase in apoptosis at the mid-domestication stage (D7), which returned to baseline levels later (D14), whereas hepatic apoptosis showed no significant changes throughout the process; (3) transcriptome sequencing identified 3405 and 881 differentially expressed genes (DEGs) in the liver and gill tissues, respectively, and the significantly enriched pathways were steroid biosynthesis in the liver and alanine, aspartate, and glutamate metabolism in the gills. The apoptosis pathway was also significantly enriched in both tissues. GO analysis further indicated that the DEGs were primarily associated with metabolic processes, oxidative stress, and cell apoptosis. In conclusion, artificial feed domestication induces adaptive changes in the tissue structure and molecular profiles of the gill and liver in mandarin fish. The gill response to dietary transition is more rapid and characterized by a reversible apoptotic process, providing a theoretical foundation for understanding the stress mechanisms associated with domestication and promoting healthy aquaculture practices for this species.

Aquaculture continues to expand globally and is now responsible for providing more than half of the aquatic products consumed worldwide [...]

The reproductive behavior and nest-building activity of the sand-dwelling goby Hazeus ammophilus were investigated to examine its nesting characteristics and to determine how and why this species builds radial structures around its nests. Field observations revealed that males spawned with multiple females in open muddy-sand bottoms, using bivalve shells or fallen leaves as spawning substrates. Males cared for eggs after spawning and repeatedly mated with multiple females, suggesting a male-territory-visiting polygamous mating system. A distinctive feature of this species was the presence of radial ditches extending from the nest. These ditches developed through repeated male behaviors of digging from the nest toward the surrounding area and sweeping accumulated sand out of the nest, resulting in a crater-like structure around the nest. These behaviors may contribute to cleaning and stabilizing the spawning substrate, and the resulting structures themselves may also be involved in female mate choice. Taken together, these findings indicate that H. ammophilus has evolved a flexible reproductive strategy, and nest-building behavior possibly adapted to unstable open sandy environments, highlighting the behavioral diversity and ecological plasticity within gobiid fishes.

Marine sponges possess complex metabolic systems that support their growth, physiology, and ecological interactions. However, the primary metabolic capacity of the sponge hosts remains incompletely characterized at the molecular level. In this study, we performed de novo transcriptome sequencing of a pooled sample of three individuals of Xestospongia sp. collected in Vietnam, using a high-throughput Illumina sequencing system, to characterize the host-derived metabolic pathways. A total of 43,278 unigenes were assembled, of which 69.15% were functionally annotated using multiple public databases. Functional annotation revealed a broad repertoire of genes associated with core metabolic pathways, including carbohydrate, lipid, and sterol metabolisms, as well as cofactor-related processes. Specifically, complete pathways involved in folate biosynthesis, terpenoid backbone biosynthesis, ubiquinone (Coenzyme Q) metabolism, and steroid biosynthesis were identified, reflecting the independent metabolic framework of the sponge host. Several highly expressed genes related to these pathways, including COQ7, ERG6, NUDX1, QDPR, and PCBD, were detected, and their expression patterns were confirmed by quantitative RT-PCR. Furthermore, protein-based phylogenetic analyses indicated that these genes are closely related to homologous proteins from other sponge species, supporting their host origin. This study provides the first comprehensive transcriptomic resource for Xestospongia sp. from Vietnam, and offers baseline molecular insights into the primary metabolic capacity of the sponge host. These data establish a foundation for future investigations of sponge physiology and host–microbe metabolic partitioning.

Fisheries management in the Mediterranean Sea faces persistent challenges due to the prevalence of data-poor and data-limited stocks, small-scale multi-species fisheries, and limited long-term monitoring programs. Effective assessment methodologies are critical to ensuring sustainable exploitation, yet traditional data-rich stock assessment models remain infeasible for many Mediterranean fisheries. This review provides a comprehensive synthesis of current methodologies developed and applied to assess data-poor fisheries in the Mediterranean context. We examine catch-only approaches, length-based methods, empirical indicators, and multi-indicator frameworks increasingly adopted by the General Fisheries Commission for the Mediterranean (GFCM) and the EU’s Data Collection Framework (DCF). Special attention is given to case studies from the western, central, and eastern Mediterranean that demonstrate the opportunities and limitations of these approaches. We further explore emerging tools, including integrated modeling frameworks, simulation-based harvest control rules, and participatory approaches involving fishers’ local knowledge, to highlight innovations suited to mixed, small-scale Mediterranean fisheries. The review concludes by identifying key gaps in data collection, assessment capacity, and institutional coordination, and proposes a roadmap for improving data-poor fisheries management under Mediterranean-specific ecological, socio-economic, and governance constraints. By consolidating methodological advances and practical lessons, this review aims to provide a reference framework for researchers, managers, and policymakers seeking to design robust, adaptive strategies for sustainable fisheries management in data-limited Mediterranean contexts.

Over the past few decades, the population of cod in the Eastern Baltic has faced numerous challenges due to environmental changes, overfishing, and predation, as well as the effects of infection by third-stage larvae of the Anisakidae parasite in the liver. The aim of this study was to estimate the prevalence and infection level of Anisakidae nematodes in the Eastern Baltic cod stock over a five-year period and analyze the effect of infection on cod health condition. A total of 1946 samples of the Eastern Baltic cod (Gadus morhua) were collected and tested for the presence of Anisakidae nematode larvae. All nematodes found in livers were identified as Anisakidae with an overall prevalence of 30.9%, a mean infection density of 0.8 (median 0.4) nematodes per gram of liver tissue, and a range of 0.01–29.2 nematodes per gram. The prevalence of infection tended to increase with the age of the fish. In multivariate analysis, increasing infection intensity decreased the odds of cod having good Fulton’s and Clark’s condition scores and a hepatosomatic index (HSI) above the population average. While our study shows a clear Anisakidae effect on Fulton’s and Clark’s condition scores and the HSI, these indicators could also be influenced by other environmental, physiological, and pathological factors.

Monitoring fish skin health is essential in aquaculture, where scale loss serves as a critical indicator of fish health and welfare. However, automatic detection of scale loss regions remains challenging due to factors such as uneven underwater illumination, water turbidity, and complex background conditions. To address this issue, we constructed a scale loss dataset comprising approximately 2750 images captured under both clear above-water and complex underwater conditions, featuring over 7200 annotated targets. Various image enhancement techniques were evaluated, and the Clarity method was selected for preprocessing underwater samples to enhance feature representation. Based on the YOLOv8m architecture, we replaced the original FPN + PAN structure with a weighted bidirectional feature pyramid network to improve multi-scale feature fusion. A convolutional block attention module was incorporated into the output layers to highlight scale loss features in both channel and spatial dimensions. Additionally, a two-stage transfer learning strategy was employed, involving pretraining the model on above water data and subsequently fine-tuning it on a limited set of underwater samples to mitigate the effects of domain shift. Experimental results demonstrate that the proposed method achieves a mAP50 of 96.81%, a 5.98 percentage point improvement over the baseline YOLOv8m, with Precision and Recall increased by 10.14% and 8.70%, respectively. This approach reduces false positives and false negatives, showing excellent detection accuracy and robustness in complex underwater environments, offering a practical and effective approach for early fish disease monitoring in aquaculture.

Essential oils (EOs) are increasingly studied as natural anesthetics for fish, offering potential alternatives to synthetic agents. This systematic review aimed to summarize the effects of EOs on Oreochromis niloticus, focusing on their efficacy in inducing sedation and anesthesia, recovery times, and associated physiological responses. A comprehensive search was conducted in the Scopus, Web of Science, and Wiley Online Library databases for studies published up to 10 December 2024. Studies evaluating EOs or their main components in O. niloticus with quantitative data on anesthesia or sedation were included. From 355 records initially identified, studies meeting the inclusion criteria were analyzed qualitatively. EOs rich in compounds such as linalool, carvacrol, and pulegone effectively induced anesthesia in less than 3 min, with recovery times under 10 min, aligning with operational standards for fish anesthesia. However, some EOs caused physiological changes that may be related to stress responses. Variability in experimental protocols and incomplete reporting of chemical composition limited the comparability between studies. EOs demonstrate promising anesthetic potential for O. niloticus, representing safe and environmentally sustainable alternatives. Further standardized and controlled studies are required to confirm their safety and optimize application in aquaculture.

This study was conducted to evaluate the effects of chia seed oil (CSO; Salvia hispanica L.) on the growth performance, haematological-biochemical parameters, immune-related gene expression, and disease resistance to Aeromonas hydrophila in common carp (Cyprinus carpio). The fish were fed diets containing 0%, 0.5%, 1%, and 2% CSO for 60 days. The results showed a significant improvement in final weight, specific growth rate (SGR), and feed conversion ratio (FCR) in fish fed diets containing 1% and 2% CSO compared to the control group. Haematocrit (Hct) and haemoglobin (Hb) levels increased in the CSO groups, while serum triglyceride and cholesterol levels decreased significantly, particularly in the 1% CSO group. The observed decrease in liver enzyme activities (AST, ALT) suggested a hepatoprotective effect of CSO. In the stress test with A. hydrophila, the highest survival rate (80%) was recorded in the 2% CSO group. Furthermore, gene expression analyses performed on spleen tissue revealed an increase in the expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-8 in the groups fed with CSO, particularly at the 1% level. These findings indicate that adding 1–2% CSO to carp feed promotes growth, improves lipid metabolism, strengthens immune status, and increases resistance to bacterial infection. Consequently, the use of CSO as a sustainable and functional additive to fish oil in fish feed is suggested.

Atlantic salmon (Salmo salar) populations in the Arctic River Teno (Tana) and other North Atlantic rivers have declined at the same time as pink salmon (Oncorhynchus gorbuscha) have begun to spawn extensively in these rivers in odd-numbered years. In the River Teno, especially, the number of one-sea-year Atlantic salmon ascendants has decreased. In this short review, we assess, based on current information, how the abundance of pink salmon may weaken the survival of Atlantic salmon. Our hypothesis is based on recent evidence from Atlantic salmon in the Baltic Sea showing that the high marine lipid content in the diet of Atlantic salmon post-smolts impairs their growth and survival and is manifested in low numbers of ascendants and in poor thiamine (vitamin B1) status in both juvenile and spawning Baltic salmon. The high energy density of lipids increases the need for thiamine in the metabolism, and the high content of highly unsaturated fatty acids (n–3 HUFAs), like docosahexaenoic acid (DHA, 22:6n–3), in marine fish lipids increases the rate of lipid peroxidation, which consumes thiamine as it acts as an antioxidant against lipid peroxidation. The review presents information that could be used in planning possible future research on the topic.