Search Results (918)

Aquatic ecosystems are increasingly threatened by multiple anthropogenic stressors, notably climate change and pollution by pharmaceuticals. Global warming is predicted to raise water temperatures by 2–5 °C by the end of the century. As ectotherms, fish are particularly vulnerable due to limited thermal tolerance and temperature-dependent physiology. Pharmaceuticals are introduced into aquatic systems at concentrations ranging from ng·L⁻¹ to µg·L⁻¹, including widely prescribed classes such as antibiotics, hormones, analgesics, antifungals, and neuropsychiatric drugs. This narrative review synthesizes experimental evidence on the interactive effects of warming and pharmaceutical exposure in fish. Thirty-nine peer-reviewed studies published since 2005 were analyzed. The findings indicate that higher temperatures often exacerbate pharmaceutical-induced toxicity, altering oxidative stress, metabolism, reproduction, and behavior. Antibiotic-focused studies showed temperature-dependent acceleration of absorption, distribution, metabolism, and excretion, with shorter half-lives and reduced tissue persistence at higher temperatures. Estrogenic hormones and antifungals have been shown to interact with thermal regimes, disrupting reproductive physiology and skewing sex ratios, particularly in species exhibiting temperature-dependent sex determination. Neuropsychiatric drugs exhibited altered uptake and metabolism under warming conditions, resulting in increased brain bioaccumulation and behavioral alterations affecting ecological fitness. Analgesics and anti-inflammatories remain understudied despite their widespread use, with evidence suggesting synergistic effects on oxidative stress at elevated temperatures. Significant research gaps persist regarding chronic exposures, early developmental stages, ecologically relevant temperature scenarios, and underrepresented or absent drug classes, such as hypolipidemic drugs. Ultimately, broader and integrated approaches are needed to better understand and predict the ecological risks of pharmaceutical pollution in a warming world. Full article

Striped catfish, Pangasianodon hypophthalmus, has recently emerged as a promising candidate for Egyptian aquaculture owing to its rapid growth; however, under intensive culture, it is vulnerable to Aeromonas hydrophila. The efficacy of dietary supplementation with effective probiotic microorganisms (EPMs) in enhancing growth performance, feed utilization, physiological health, and disease resistance of P. hypophthalmus against A. hydrophila challenge was evaluated. A 90-day feeding trial was conducted with 300 fish randomly distributed into four triplicate groups (25 fish per replicate) reared in 12 indoor fiberglass tanks: a control and three groups receiving EPMs at inclusion levels of 1.5%, 3%, and 4.5%. The results showed significant, dose-dependent improvements across all EPMs-supplemented groups in survival, growth rates, feed utilization, and hematological parameters (RBC, Hb, PCV, WBC, and lymphocytes). Dietary EPMs led to significant improvements (p ≤ 0.001) in digestive efficiency, protein and lipid metabolism, antioxidant enzyme activity, immune performance, and the ability of striped catfish to withstand A. hydrophila infection. Hepatobiliary enzyme activities (ALT, AST, and ALKP), glucose levels, lipid profile markers, and hepatic MDA exhibited a significant linear decrease (p ≤ 0.0001) with increasing EPMs levels. The gut microbial composition showed a dose-dependent increase in beneficial lactic acid bacteria (LAB) and a reduction in TAPC, pathogenic coliforms (TFCC), and Vibrio spp. (TVC). These results demonstrate the dose-dependent effects of EPMs on enhancing aquafeed efficiency, overall health, and innate immunity in striped catfish. Full article

To explore the induction of low temperature the Tiger Puffer (Takifugu rubripes) In this study, the influence of temperature on the pituitary gland during masculinization was investigated through chronic hypothermia stress experiments. Metabolomics was used to analyze the metabolic regulatory network of the pituitary gland under hypothermia stress. ELISA technology was employed to determine the activity content of oxidative stress-related enzymes in the pituitary gland. Further, TUNEL fluorescence labeling and qPCR were used to detect the apoptosis level of pituitary cells. Finally, to assess the impact of low-temperature stress on muscle tissue, HE staining and qPCR techniques were employed. The results showed that after 45 days of low-temperature stress, the differential metabolites of the pituitary gland were mainly enriched in the amino acid metabolic signaling pathway, and the contents of amino acids such as GSH and its synthetic precursors in the pituitary tissue changed significantly. The contents of oxidative stress indicators such as ROS and MDA all showed a trend of first increasing and then decreasing. The qPCR results of TUNEL fluorescence labeling and apoptosis-related genes were consistent, indicating that the apoptotic level of pituitary cells first increased and then decreased with the stress process. Histological analysis revealed that low temperature led to muscle cell atrophy and increased interstitial space in muscle tissue. The expression changes in genes related to muscle development further confirmed that low temperature significantly inhibited muscle growth and development. Therefore, this study speculates that after being subjected to chronic low-temperature stress, the pituitary gland of the red-finned Oriental pufferfish can alleviate the oxidative stress response of the body by strengthening the amino acid metabolic pathway, and the fish body has shown a physiological trend of gradually adapting to low-temperature stress, but the growth and development of muscles are still significantly inhibited. The results of this study can provide theoretical support for understanding the physiological adaptation mechanism of the red-finned Oriental pufferfish to low-temperature stress and lay a foundation for subsequent in-depth exploration of the pituitary response mechanism to low temperatures. Full article

Carbon quantum dots (CQDs) are photoluminescent nanomaterials (<10 nm) with excellent hydrophilicity, biocompatibility, and low cytotoxicity, making them attractive for biological applications. However, their use in aquaculture nutrition has remained largely unexplored. This study investigated the effects of dietary CQDs on zebrafish (Danio rerio), a model organism with approximately 70% genetic homology with humans. CQDs were synthesized hydrothermally from unripe Citrus limon and characterized by UV–visible (UV-Vis) spectroscopy, UV–vis transillumination, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FT-IR), and photoluminescence (PL) spectroscopy. Zebrafish were fed diets containing varying CQD concentrations, and growth performance, condition factor (K), hematological parameters, enzymatic activity, and tissue morphology were assessed. Feeds supplemented with 2 mL CQDs produced significant improvements in growth and biochemical indicators without adverse effects. Hematological and enzymatic profiles remained within normal ranges, and histological examination revealed no morphological abnormalities, indicating the absence of toxicity. These findings suggest that citrus-derived CQDs can enhance zebrafish growth and maintain physiological health, thereby supporting their potential as safe functional feed additives in aquaculture. This approach may open new opportunities for the application of CQDs in sustainable fish farming and the broader food industry. Full article

Aquaculture faces challenges in reducing feed costs while promoting sustainable use of by-products. This study aimed to evaluate the effects of totally replacing soybean oil (SBO) with fish by-product oil (FBO) in the diet of Colossoma macropomum, focusing on growth performance, physiological and hepatic responses, meat composition, and economic viability. A total of 360 juveniles (9.1 ± 0.59) were distributed in a randomized design with six treatments (0–100% SBO replacement) and six replicates each, and fed to apparent satiation for 91 days. Growth performance did not differ significantly among treatments (p > 0.05), although fish receiving 40% FBO achieved the best feed conversion ratio among treatments. Hematological and biochemical analyses indicated that higher FBO levels (particularly 100%) indicating subtle yet adaptive physiological adjustments, such as moderate modulations in lipid metabolism and erythropoietic activity. Liver weight and hepatosomatic index decreased linearly with increasing FBO levels. In meat composition, FBO inclusion enhanced protein and reduced lipid contents. Although economic indicators were not statistically different (p > 0.05), offered the most favorable trade-off between biological performance and economic efficiency. These findings demonstrate that partial replacement of SBO with FBO, particularly at 40%, represents a sustainable and economically viable alternative for C. macropomum farming. Full article

This study aimed to explore the effects of dietary rapeseed meal replacing fish meal on growth performance, intestinal structure, gut microbiota, and related gene expression of juvenile largemouth bass (Micropterus salmoides). Five isonitrogenous and isolipidic diets were designed, in which rapeseed meal replaced 0% (FM, control), 5% (RM5), 10% (RM10), 15% (RM15), and 25% (RM25) of fish meal. Then, largemouth bass (11.00 ± 0.20 g) were randomly and equally allocated to 15 experimental tanks (25 fish per tank) for an 8-week feeding trial. The results showed that growth performance declined as replacement levels increased to 25%. However, the RM5 group had the highest body crude protein, distal intestinal muscle layer thickness (MLT), and plica height (PH) and width (PW), which were significantly higher than those of the FM group. In addition, compared to the FM group, the RM15 and/or RM25 groups had higher levels of D-lactic acid, diamine oxidase, and lipopolysaccharide. Furthermore, the RM25 group exhibited higher abundances of Lactococcus and Weissella but lower levels of Aeromonas and Staphylococcus compared to the FM group. Intestinal transcriptome analysis revealed that the PI3K-Akt and NF-κB signaling pathways were significantly up-regulated when comparing the RM25 and FM groups. The results demonstrate that the replacement of 5% fish meal with rapeseed meal did not have a negative impact on the physiological status of largemouth bass. However, a replacement level of 25% reduced growth performance and damaged intestinal structure, potentially by altering the abundance of intestinal microbiota and up-regulating the PI3K-Akt and NF-κB signaling pathways. Full article

The revalorization of animal by-products, such as porcine blood, is a key strategy for sustainable aquaculture and circular economy practices. This study aimed to fill the existing knowledge gap on the effects of spray-dried porcine blood hydrolysate (PBSH), assessing its potential as a functional feed ingredient for gilthead sea bream. Two practical diets were formulated: a control diet containing 5% blood meal, and a PBSH diet including 5% PBSH previously characterized in vitro. The results indicated that the PBSH diet promoted lower hepatosomatic index, a down-regulation of key hepatic lipogenic enzymes (scd1b, hl, lpl), and a better stress condition with lower circulating levels of glucose and cortisol and a reduction in aggressive attacks. Positive findings were also achieved in energy management, obtaining lower metabolic rates along with an enhanced swimming performance (20% increase in the critical speed) and a quicker weigh recovery after a fasting period. The PBSH diet also shaped the intestinal bacterial composition, determining a redistribution of abundant genera including Aureimonas and Halomonas. Ultimately, this study demonstrated that PBSH would act as a functional ingredient capable of enhancing fish energy management and resilience in the face of stressful events, exhibiting a transient transcriptional modulation, yet persistent physiological and welfare benefits. Full article

The Xingkai Lake topmouth culter (Culter alburnus) is an endemic, economically valuable fish in Heilongjiang that is highly sensitive to ammonia. However, the systemic effects of acute ammonia stress on its liver have not been determined. The objective of this study was to elucidate the changes in and relationships among stress biomarkers, antioxidant defense mechanisms, apoptosis indicators, and histopathological alterations in the liver of C. alburnus, a fish species native to Xingkai Lake, China, under acute ammonia exposure. Guided by the findings of a 96 h-LC₅₀ assay, the researchers subjected the fish to 48 h of acute exposure at specified total ammonia nitrogen (TAN) concentrations of 30 mg/L, 36 mg/L, and 40 mg/L. A comprehensive assessment of physiological and biochemical markers, including cortisol (COR), blood ammonia (Amm), blood glucose (Glu), aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA), revealed pronounced physiological stress and oxidative damage, particularly in the high-concentration groups. The physiological effects of ammonia exposure on C. alburnus showed a clear concentration and time dependence. Notably, elevated ammonia levels significantly upregulated apoptosis-associated genes such as P53, Bax, and Caspase-3. These findings were further substantiated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays and histopathological examinations. Overall, the study demonstrated that acute ammonia exposure exerted substantial impacts on the physiological, biochemical, and genetic expression profiles of C. alburnus in Xingkai Lake, leading to sustained stress and oxidative damage, especially at elevated concentrations (30–40 mg/L). Full article

Aquaculture is expanding rapidly worldwide, but its sustainability is threatened by intensive production practices, environmental stressors and recurrent disease outbreaks. Natural feed additives are increasingly studied as alternatives to antibiotics and synthetic compounds. Among them, bee-derived products—pollen, bee bread, propolis, royal jelly, honey and fermented derivatives—represent a promising resource due to their richness in proteins, amino acids, fatty acids, vitamins, flavonoids and phenolic compounds with demonstrated antioxidant, antimicrobial and immunostimulant properties. Evidence from studies on species such as Nile tilapia, rainbow trout, European sea bass, meagre and African catfish indicates that dietary supplementation with bee products can improve growth performance, immune and antioxidant responses, stress tolerance and resistance to bacterial infections while, in some cases, enhancing the nutritional value and shelf-life of fish products. Prominent examples include ~45% higher growth in African catfish with 10–30 g kg⁻¹ bee pollen, up to 93% protection in Nile tilapia fed 25 g kg⁻¹ pollen against Aeromonas hydrophila, and increased trout fillet carotenoids with pollen-derived pigments (with overall growth unchanged and pigmentation lower than synthetic astaxanthin). Conversely, meagre fed 20–40 g kg⁻¹ raw pollen showed reduced growth and digestibility with elevated intestinal stress markers, underscoring species- and dose-specific responses. Nevertheless, the available data remain fragmented and heterogeneous, reflecting differences in product type, origin, dosage and experimental design. This review critically analyses the current knowledge on bee products in aquaculture nutrition, identifies the main gaps and limitations, and outlines future research directions. By linking fish physiology, nutritional strategies and product quality, bee-derived products emerge as innovative tools for promoting fish health and resilience in sustainable aquaculture. Full article

Percocypris pingi is an endangered protected fish species in China. Its albino variants exhibit growth retardation and physiological abnormalities. Understanding its albinism mechanism holds significant scientific importance for molecular breeding programs and disease model development. This study integrated transcriptomic and proteomic analyses, combined with histopathological and molecular biological techniques, to systematically compare molecular differences in skin tissues between albino and wild-type P. pingi, with a focus on elucidating the multidimensional regulatory mechanisms underlying skin albinism. Our findings suggest that albinism in P. pingi is synergistically driven by hyperactivation of ubiquitin-mediated proteolysis (which suppressed TYR/TYRP1 enzymatic activity and disrupted the pH homeostasis of melanosomes), and inhibition of calcium signaling (which impeded melanin transport). This discovery provides novel insights into the mechanisms of pigment loss in fish species and offers a valuable reference for molecular breeding of endangered species as well as research on pigmentation-related disorders. Full article

Salinity is a pivotal environmental factor that significantly influences the survival, growth, development, and reproduction of aquatic organisms. However, the characteristics of serum metabolites and their mechanistic roles in mediating the response of grass carp (Ctenopharyngodon idellus) to long-term salinity stress remain incompletely understood. Therefore, the present study exposed grass carp to different salinity levels (0, 4, and 8 g/L) for 60 days to evaluate the associated physiological alterations and metabolic responses. The results revealed that high salinity (8 g/L) significantly suppressed growth performance (p < 0.05), whereas low salinity (4 g/L) caused no significant reduction in growth or survival. Physiological analyses indicated that fish in the 8 g/L group exhibited markedly reduced levels of lactic acid and total protein, along with elevated concentrations of total cholesterol, triglycerides, glucose, and glutamic-oxaloacetic transaminase (p < 0.05). Serum ion homeostasis was also disrupted under high salinity, characterized by increased Ca²⁺, Na⁺, and Cl⁻ levels and decreased Mg²⁺ (p < 0.05). Furthermore, oxidative stress was evident in the high-salinity group through heightened activities of antioxidant enzymes (SOD, CAT, GPx), accumulation of oxidative damage markers (protein carbonyl, 8-OHdG) (p < 0.05). Metabolomic profiling identified 367 and 403 significantly altered metabolites in the 4 g/L and 8 g/L groups, respectively, primarily belonging to lipids and lipid-like molecules along with organic acids and derivatives. KEGG enrichment analysis revealed that these differential metabolites were chiefly involved in amino acid biosynthesis, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acids, and glycine, serine, and threonine metabolism. Trend analysis further uncovered eight distinct expression patterns of metabolites across salinity gradients. These results provide novel insights into the metabolic adaptations of grass carp to salinity stress, demonstrating that high salinity induces oxidative stress, disrupts ion regulation, and drives extensive metabolic reprogramming. The study offers valuable theoretical support for improving salinity tolerance management in aquaculture and informs the selective breeding of salt-tolerant fish strains. Full article

The nutritional value of a diet and its bioavailability in fish depend on three primary capacities: (a) ingestion, (b) digestion, and (c) absorption. Among these, digestive capacity, defined here as the total enzyme activity available to hydrolyze the bonds of dietary macromolecules to obtain hydrolysis products that are ultimately converted into absorbable micromolecular units, establishes the upper limit for the bioaccessibility of nutrients. To clarify usage and measurement, we conducted a systematic SCOPUS survey (January 2020–June 2024; 62 relevant articles). Most studies either omit a clear definition of digestive capacity or conflate it with digestive organ morphology or isolated enzyme activities. We compared indicators and assay conditions (substrate type, pH, temperature, and expression of units), revealing significant inter-study variability. Based on this synthesis, we propose four operational definitions: (a) Extract Theoretical Volume (ETV)—calculated volume of extract, considering both the solvent volume (SV) used for tissue homogenization and the tissue’s water content; (b) digestive capacity (U)—the total catalytic activity present in the digestive tract at the moment of sampling, where 1 U is the amount of enzyme catalyzing the formation of 1 µmol of product per minute under species-specific physiological pH, ionic strength, and temperature, with the total activity expressed as U fish⁻¹, U organ⁻¹, or U g⁻¹ fish or U g⁻¹ organ, enabling direct comparisons across studies; (c) Digestive Processing (DP)—the total number of bonds hydrolyzed during a given digestion time, whether instantaneous or over a defined period; and (d) Digestive Processing Index (DPI, U-min or U-h), which integrates digestive capacity over time. This framework provides a harmonized checklist for assay standardization and advances comparative studies in fish digestive physiology. Full article

Rapid urbanization and increased anthropogenic activities have led to the release of an increasing number of pollutants, including metals, into freshwater ecosystems, posing a significant threat to aquatic life. In this study, the bioaccumulation of metals and hepatic enzyme activities in northern pike (Esox lucius) from two contrasting freshwater ecosystems in Serbia, the lotic Tisza River and the lentic Bela Crkva Reservoirs, were investigated. A total of 22 specimens (11 per site) were sampled in autumn 2024. The liver tissue was analyzed for the concentrations of 11 metals (As, Cd, Cr, Co, Cu, Pb, Li, Fe, Zn, Mn, Ni) and the activities of the liver enzymes (ALT, AST, AP, GGT). The results showed ecosystem-specific patterns of metal accumulation, with the northern pike in the rivers showing significantly higher Cu and Fe levels, while the fish in the reservoirs showed increased Zn concentrations. Enzymatic biomarkers showed different responses between ecosystems, with river fish showing increased ALT and AST activities, indicating hepatocellular stress, while reservoir fish showed increased GGT, indicating enhanced detoxification processes. The body condition factor was negatively correlated with liver Mn and Zn concentrations, emphasizing its utility as an integrative bioindicator of metal-induced stress. No significant sex-specific differences in metal or enzyme levels were found. These results suggest the suitability of northern pike as a sentinel species for environmental monitoring in freshwaters and highlight the different physiological adaptations to local metal stress in lentic and lotic habitats. Full article

In recent years, toxicological studies on fish exposed to emerging contaminants (ECs) have been relatively in-depth. However, research on trans-/multi-generational exposure of fish to ECs remains scarce. Limited data indicate that when parental generations (P) are subjected to ECs stress, it can threaten the normal transmission of functions in offspring, such as growth and development, reproduction, physiology, endocrine, neural, and behavioral functions. Even after the exposure is terminated, these negative impacts may persist. Under the long-term presence of ECs, the health of fish offspring may affect the survival of entire populations and the stability of ecosystems. Therefore, this review summarizes studies on trans-/multi-generational effects of ECs on fish and analyzes these research results. Based on the materials collected, more research on trans-/multi-generational ECs effects on fish is urgently needed, especially regarding the F3 generation, combined toxicity, and trans-/multi-generational epigenetic effects. This will enable a comprehensive assessment of the health and ecological risks posed by ECs at environmental concentrations to fish. Full article

The sustainability of aquaculture is increasingly threatened by rising ocean temperatures occasioned by the continued prevalence of global warming, which can have severe consequences for fish health and productivity. Fish, as ectothermic organisms, are susceptible to temperature fluctuations and prolonged exposure to extreme temperatures can lead to physiological disruptions, including altered metabolic rates, oxidative stress, and immune suppression, ultimately affecting their growth and reproductive success. In response, several strategies, including dietary supplementation, have been proposed to alleviate temperature stress in aquaculture. One such supplement, gamma (γ)-aminobutyric acid (GABA), a non-proteinogenic amino acid, has garnered attention for its potential to enhance stress resilience in aquatic species. In this review, we examine the physiological responses of fish to temperature stress and evaluate the role of GABA in alleviating non-temperature stress. By synthesizing the available evidence, we aim to highlight the potential of GABA as a dietary supplement to improve the resilience of farmed fish to temperature fluctuations, ultimately contributing to sustainable aquaculture in the face of climate change. GABA acts as an inhibitory neurotransmitter in the central nervous system, promoting relaxation and reducing stress. We not only spotlight GABA’s role in the central nervous system, where it has been shown to modulate stress responses by enhancing antioxidant defenses, improving growth performance, and boosting disease resistance, but also emphasize the limited exploration of its potential to mitigate temperature stress in some aquaculture species, particularly economically important fish like olive flounder. Finally, in this review, we provide additional insights into how GABA might help mitigate temperature stress by identifying factors that may influence its supplementation, thereby laying the groundwork for future research on its use as a potential tool for mitigating temperature stress in aquaculture species. Full article