Search Results (1,957)

The nitrogen budget and the effects of varying densities of sea grape (Caulerpa lentillifera) on water quality and the growth performance of Asian seabass (Lates calcarifer) in a polyculture system were evaluated. Four treatments were tested, each stocked with 20 fish (average weight: ~20 g; density: 2.66 kg/m³). Treatment 1 (control) contained no sea grapes, while treatments 2, 3, and 4 included 100, 200, and 400 g of sea grapes, corresponding to 0, 667 g/m³, 1333 g/m³, and 2666 g/m³, respectively. Significant (p < 0.05) reductions in total ammonia nitrogen (TAN), total suspended solids (TSS), and turbidity were observed with increasing sea grape density; however, no significant differences (p > 0.05) were found among the three sea grape treatments. Higher sea grape densities increased nitrite (NO₂–N) and nitrate (NO₃–N) concentrations due to enhanced nitrification. Approximately 65% of the nitrogen input originated from feed, but only 47.78–48.96% was assimilated into fish biomass. Nitrogen losses included 1.17–1.46% via water exchange and final drainage, while 45.27–50.76% was likely retained in sediments, volatilized, or lost through denitrification. Sea grapes effectively absorbed total nitrogen (TN), demonstrating their potential as biofilters for improving water quality without compromising fish growth performance. The optimal density was 100 g of sea grapes per 2.66 kg/m³ of seabass biomass, offering a sustainable strategy to enhance productivity while mitigating environmental impacts. Full article

We sought to develop and evaluate an escape vent designed for undersized swimming crabs (Portunus trituberculatus) to reduce bycatch, contributing to the preservation of marine resources. To this end, we conducted aquarium experiments and selectivity analysis to determine the appropriate size of the escape vent that would allow only undersized crabs with a carapace length of 64 mm or less to escape. The optimal dimensions for the escape vent were approximately 34.1 mm in height and 69.1 mm in width. During the sea trial, the average bycatch rates for undersized crabs per pot were 57.2%, 15.0%, and 22.3% for the control, basic, and door types, respectively. Regarding legal-sized crab catch per pot, averages of 1.40, 1.72, and 1.62 individuals were obtained for the three pot types. To our knowledge, this study is the first to assess the optimal size for an escape vent capable of reducing the bycatch of undersized crabs while maintaining legal-sized swimming crabs capture. Full article

Food webs in estuarine ecosystems serve as important biological indicators. The feeding ecology of four keystone fish species, pikeperch (Sander lucioperca L.), smelt (Osmerus eperlanus L.), ruffe (Gymnocephalus cernua L.) and flounder (Platichthys flesus L.), in the Elbe and Odra estuaries was analyzed using stomach content analyses. Important prey of pikeperch were fishes and mysids in both estuaries. Amphipods were especially important as prey for smelt in the Elbe estuary, whereas smelt caught in the Odra estuary mainly consumed mysids. Ruffe fed mainly on amphipods in the Elbe estuary, while annelids (lower section) and insect larvae (upper section) were the most important prey in the Odra estuary. Flounder favored copepods as prey in the Elbe estuary, while bivalves were preferred in the Odra estuary. Higher dietary overlaps were found in the Elbe estuary between smelt vs. ruffe, pikeperch vs. ruffe, and pikeperch vs. smelt. In the Elbe estuary, a shift in the diet composition of pikeperch, smelt, and ruffe was observed from 2021 to 2022 compared to food analyses from the 1990s. These shifts included an increased consumption of amphipods, while mysids and copepods had recently decreased in their diets. These changes indicate a restructuring of the food web, potentially linked to environmental changes, which highlights the sensitivity of estuarine ecosystems. Full article

This study investigates the age, growth, and mortality of the common pandora (Pagellus erythrinus) in the Central Aegean Sea, providing critical insights into its population dynamics and sustainability. A total of 589 specimens were analyzed, identifying nine age cohorts with mean total lengths ranging from 13.18 cm to 32.94 cm. Growth parameters, estimated using the von Bertalanffy growth model, yielded an asymptotic length (L∞) of 39.53 cm and a growth coefficient (k) of 0.16 year⁻¹, indicating moderate growth rates. The population exhibited non-isomorphic growth (b = 2.49, R² = 98.4), suggesting slower weight gain relative to length. Mortality estimates indicated natural mortality (M) at 0.321 year⁻¹, total mortality (Z) at 0.52 year⁻¹, and fishing mortality (F) at 0.2 year⁻¹, resulting in an exploitation rate (E) of 0.38. The fishing mortality at maximum sustainable yield (FMSY) was estimated at 0.33, with an exploitation rate at MSY (EMSY) of 0.51, suggesting that the population is currently harvested sustainably but close to the threshold of overexploitation. These findings provide essential reference points for fisheries management and highlight the need for continuous monitoring to ensure the long-term sustainability of P. erythrinus in Greek waters. Full article

Astaxanthin, a xanthophyll carotenoid, exhibits potent biological functions, including antioxidant, immune regulation, growth promotion, improved reproductive capacity, and enhancement of the body color of aquatic animals. In recent years, with the rapid development of the aquaculture industry, the application of astaxanthin in aquaculture has garnered increasing attention. Studies have demonstrated that astaxanthin significantly enhances the antioxidant capacity of aquatic animals, reduces oxidative damage, and regulates the expression of immune-related genes, thereby improving immunity and disease resistance. Moreover, astaxanthin promotes growth and reproductive performance, particularly in high-value aquaculture species, where it also serves as a natural pigment to increase market competitiveness. However, the low bioavailability and high production costs of astaxanthin remain major constraints to its widespread use in aquaculture. To address these limitations, various strategies—such as microencapsulation, liposomal delivery, and nanotechnology—have been explored to improve its stability and water solubility. Additionally, expanding astaxanthin sources and optimizing production processes are effective approaches to reducing costs. This review summarizes recent advances in astaxanthin research within aquaculture, highlights its multifunctional roles in promoting the health and production efficiency of aquatic animals, and discusses the current challenges and future research directions. Full article

The mercury (Hg) present in ocean fish has caused concern regarding the effects of maternal consumption on child outcomes but it is now recognized that mothers that eat more ocean fish during pregnancy have children with higher social, scholastic, and IQ scores. These findings coincide with the current understanding of the mechanism of Hg toxicity which indicates ocean fish consumption will prevent rather than cause harm. High-Hg exposures sequester selenium (Se) and inhibit Se-dependent enzymes that prevent and reverse oxidative damage in the brain and support fetal brain development. However, aside from certain types of shark and other apex marine predators, seafood contains more Se than Hg and thus counteracts instead of contributing to Hg toxicity. This study evaluates the Hg and Se present in bigeye tuna, yellowfin tuna, albacore tuna, skipjack, swordfish, striped marlin, blue marlin, spearfish, mahimahi, wahoo, monchong, escolar, mako shark, and thresher shark to establish their health benefit values (HBVs). Positive HBVs (0.3–19.6), indicating a molar excess of Se over Hg, were found in 14 of the 15 species studied. Only mako shark uniformly contained Hg in excess of Se to produce a negative HBV (−16.4), indicating its consumption should be minimized during pregnancy. Full article

Discogobio is a genus of small, economically important freshwater fishes that are widely distributed in Southwestern China. The species of the genus are morphologically very similar, which makes their taxonomic identification quite challenging. DNA barcoding technology can identify species at the molecular level, thus overcoming the limitations of morphological classification. In this study, we collected 16 morphological species of Discogobio from China, analyzed the mitochondrial cytochrome oxidase I subunit (COI) gene sequences of 206 samples, and applied DNA barcoding to identify the species. The COI amplicon was 651 bp in length, and the mean base contents were: (T) 28.83%, (C) 27.63%, (A) 25.97%, (G) 17.57%. The AT content (54.8%) was higher, and the base composition was biased. The intraspecific differences in the genus Discogobio were not significant, and the genetic distances were all less than 2%. The average interspecific genetic distances (3.94%) were about 18.8 times the average intraspecific genetic distances (0.21%), suggesting that there are barcode gaps among the species of the genus Discogobio. Five different species definition methods, Automatic Barcode Gap Discovery (ABGD), Assemble Species by Automatic Partitioning (ASAP), Bayesian Poisson Tree Process (bPTP), Generalized Mixed Yule Combination (GMYC), and Refined Single Linkage (RESL), were used to infer molecular operational taxonomic units (MOTU). The number of MOTUs ranged from 9 to 18. Phylogenetic analysis based on COI gene haplotypes showed that most species formed well-evolved branches on the phylogenetic tree, and the clustering among species was obvious without mixing. The results of this study provide reliable DNA barcoding information for species identification within the genus Discogobio, which is of great significance for taxonomic identification. Full article

A critical distinction often overlooked, yet rudimentary to the sustainable infrastructure of a complex and generative industry, is the fundamental difference between animal health and welfare in aquaculture. While these terms are frequently used interchangeably by producers, advocates, and policymakers, understanding how they both correlate and deviate from one another in commercial farming practices is an essential element of sustainable development with animal welfare as a priority, rather than a mere formality. This review represents a turn of the tide where we aggregate effective examples of actionable blueprints the seafood industry can use to elevate and replicate responsible practices in modern aquaculture. These practices must be designed to respect the interests of all stakeholders, including the animals farmed, and ensure that their quality of life in captivity is not just maintained but enhanced. The importance of incorporating animal welfare into decision-making processes, as it is closely tied to public health and environmental sustainability, has garnered attention in recent years with no indication of fleeting interest. Articulating the observed benefits in farming operations that have adopted positive welfare processes can expose a more sustainable, harmonious relationship between producers and animals in the seafood industry and help facilitate meaningful progress with collective buy-in. Full article

Cymothoidae (Crustacea: Isopoda) infest fish in marine, brackish, and freshwater environments. Cymothoa pulchrum Lanchester, 1902 is a cymothoid commonly found in the buccal cavity of mainly Tetraodontiformes fishes, distributed in the central and western Indo-Pacific region. This study describes the morphology of each life cycle stage of C. pulchrum: adult female, transitional, adult male, juvenile, and manca. In addition, we obtained DNA sequences linked to the morphological information of this species. We compared it with the sequences in the database using the neighbor-joining tree based on cytochrome c oxidase subunit I (COI) and 16S rRNA. Prior to this study, morphological data on the immature stages of Japanese Cymothoa was limited to juveniles of Cymothoa indica Schioedte and Meinert, 1884. The research identified 12 distinct morphological features that differentiate juvenile C. pulchrum from juvenile C. indica. Molecular analysis revealed that the COI sequences obtained in this study matched some of the C. pulchrum sequences in the database, whereas other sequences in the database formed a clade with Cymothoa eremita (Brünnich, 1783). In the phylogenetic tree based on 16S rRNA, C. pulchrum was also divided into two groups. In the COI phylogenetic tree, C. pulchrum and C. eremita form a total of five groups, and these two species might need to be re-examined taxonomically and molecularly. Full article

Recent interest in integrated multi-trophic aquaculture (IMTA) as an ecologically-sustainable and climate-conscious aquaculture system has resulted in testing different species partnerships and configurations in anticipation of industrialization. Deposit feeders like the California sea cucumber (Apostichopus californicus) have been suggested as ideal partners for IMTA with finfish, due to their ability to consume fish waste as well as their passive nature. However, the nutritional impacts of feeding on fish waste in IMTA have not yet been established for this species. The present study tested the effect of 3 months of inclusion in IMTA with Chinook salmon (Oncorhynchus tshawytscha) on the fatty-acid and nitrogenous-metabolite profiles of California sea cucumbers. The fatty-acid profiles of IMTA sea cucumbers showed significant changes from wild reference individuals, while few differences were detected in amino acids and other nitrogenous metabolites. Sea cucumbers housed directly in cages with salmon showed distinct shifts in their fatty-acid profiles toward higher levels of MUFAs and lower levels of SFAs, while PUFA concentrations remained the same. Sea cucumbers included in IMTA with finfish may be even more healthful for humans due to the accumulation of certain unsaturated fatty acids in their tissues not seen in wild reference individuals. Full article

Edwardsiella tarda is a gram-negative bacterium reported to be one of the most harmful pathogens in aquaculture. In this study, we conducted transcriptome profiling of the head kidney, liver, and spleen in spotted sea bass (Lateolabrax maculatus) infected with E. tarda. A total of 22,015 unigenes were detected by de novo assembly and annotated by comparison with the major databases (NR, GO, COG, KEGG, Swiss-Prot), with 21,065 (NR:95.68%), 11,320 (GO:51.42%), 20,464 (COG:92.95%), 21,295 (KEGG:96.73%), 18,791 (Swiss-Prot:82%). Subsequently, a substantial number of differentially expressed genes (DEGs) were identified (p-adjust < 0.05). In the head kidney, liver, and spleen, there were 1302 upregulated genes and 503 downregulated genes, 377 upregulated genes and 530 downregulated genes, and 1240 upregulated genes and 736 downregulated genes, respectively. Additionally, the expression levels of eight immune-related DEGs were validated by qRT-PCR, further verifying the reliability of the transcriptome data. To the best of our knowledge, this is the first analysis of the transcriptome profile of L. maculatus in response to E. tarda. These findings not only offer fundamental insights into the antibacterial immune mechanisms of spotted sea bass but also serve as a reference for formulating more effective fish disease management strategies. Full article

The influence of dietary glutamate (Glu) was evaluated in a 56-day feeding trial on the growth performance and flesh quality of largemouth bass (Micropterus salmoides). A total of 1170 fish (average body weight 24.05 ± 0.22 g) were randomly allocated into six groups, with three replicates per group. They were fed diets containing Glu in levels of 11.40% (G1), 11.88% (G2), 12.53% (G3), 13.27% (G4), 14.33% (G5), and 15.62% (G6). We found that, over a 56-day feeding period, the final body weight (FBW) of largemouth bass was about 4–5 times the IBW. The FBW, percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) initially increased and then decreased with elevating dietary Glu levels. Likewise, protein content, lipid content, apparent digestibility coefficient of dry matter (ADC_D), and apparent digestibility coefficient of protein (ADC_P) followed a similar pattern. Supplementation with Glu significantly improved the hepatosomatic index (HSI), viscerosomatic index (VSI), and relative gut length (RGL). Moreover, dietary Glu augmentation noticeably enhanced flesh composition such as muscle protein, ash, lipid, amino acid contents, and polyunsaturated fatty acids (PUFAs). Furthermore, dietary Glu supplementation enhanced muscle physicochemical quality (such as drip loss and pH), textural properties (adhesiveness and cohesiveness), and biochemical indices such as total protein (TP) and salt-soluble protein, while decreasing muscle cathepsin B (CtsB) and lactate dehydrogenase (LD) contents, thereby improving flesh quality. In conclusion, these findings suggest that Glu plays a crucial role in enhancing both growth performance and muscle quality in largemouth bass. The optimal dietary requirement for juvenile largemouth bass was estimated to be approximately 125.1 g/kg of diet based on SGR analysis. Full article

Microplastic pollution in the environment has greatly increased due to the widespread use of plastics. Antibiotics and microplastic are common contaminants, especially in aquaculture. Microplastics could act as antibiotic vectors that raise the potential of their ecotoxicological effects. In this work, we conducted several analyses of biomarker responses to examine the developmental toxicity and toxicological endpoints that polyethylene microplastics (PE-MPs) and tetracycline antibiotics (TC) induced in zebrafish (Danio rerio) embryos/larvae. The results suggested that TC-PE-MPs induced significant physiological perturbations, including attenuated spontaneous cardiac contractions, cardiotoxicity, a dose-dependent elevation in mortality, and a marked reduction in body length, accompanied by morphological alterations. The mechanistic analysis revealed that ROS accumulation triggered enzymatic activity changes, which further induced aberrant vascular development, robust inflammatory responses, and dysregulated gene expression. These findings demonstrate that PE coexistence potentiates TC’s toxicological effects, with combined exposure inducing developmental toxicity during critical organogenesis stages in zebrafish. Overall, the current research demonstrated the detrimental effects of TC-PE-MPs on early fish development, suggesting potential environmental risks. Full article

The growing aquaculture industry has an increasing demand for novel, sustainably produced protein sources for aquafeed. This study aimed to determine the apparent digestibility (AD%), pellet quality, and protein score of four novel fungal proteins in rainbow trout (Oncorhynchus mykiss), namely, PEKILO^® (PEK) derived from Paecilomyces variotii, Aspergillus oryzae (AO), Rhizopus oligosporus (RO), and Rhizopus delemar (RD). All fungi were grown on various side-streams, such as beet vinasse, thin stillage, and whole stillage. The diets were produced by extrusion technology and consisted of control and test diets with a 30:70 test ingredient/control ratio. Feeding lasted for 39 days. Each tank had 20 fish, with three replicates per dietary treatment. One-way ANOVA was performed to compare the means of the groups with each other. The dry matter (DM) digestibility of PEK was significantly higher than that of AO, RD, and RO, all with similar digestibility. The crude protein AD% for PEK was 86.5%, which is significantly higher than that of the other fungal sources. AO, PEK, RD, and RO had similar crude fat AD% compared to each other, at 83.8%, 87.4%, 90.5%, and 88.5%, respectively. The pellet quality was found to deteriorate with addition of fungal proteins. PEK had high AD% for most of the macronutrients tested and better pellet quality. Full article