Search Results (315)

Global food production systems are increasingly challenged by population growth, climate change, water scarcity, and environmental degradation, necessitating the adoption of sustainable, resource-efficient food production strategies. Aquaponic systems integrate recirculating aquaculture with hydroponic crop cultivation, enabling nutrient recycling and improved water-use efficiency. Simultaneously, CRISPR/Cas9 genome-editing technology has emerged as a powerful tool for precise genetic improvement of economically important aquaculture traits. This review critically evaluates current progress in CRISPR/Cas9 applications in aquaculture, with emphasis on Nile tilapia (Oreochromis niloticus). Evidence from peer-reviewed studies indicates that targeted modification of genes associated with growth regulation, disease resistance, nutrient metabolism, feed efficiency, and stress tolerance can significantly enhance fish productivity and physiological resilience. Genes involved in hypoxia adaptation and nitrogen metabolism may further improve environmental performance in intensive recirculating systems by reducing ammonia accumulation and enhancing nutrient utilization. However, most genome-editing studies have been conducted under laboratory or conventional aquaculture conditions, with limited information available regarding the long-term performance, ecological interactions, microbial dynamics, and biosafety of genome-edited fish in aquaponic environments. Technical limitations including off-target effects, mosaicism, delivery efficiency, regulatory uncertainty, and public acceptance continue to constrain large-scale implementation. In the short term, CRISPR/Cas9 applications are likely to focus on practical trait enhancement under controlled aquaculture systems, whereas longer-term research may explore fish lines specifically optimized for nutrient cycling, environmental resilience, and integrated aquaponic sustainability. Overall, CRISPR/Cas9-mediated genome editing represents a promising but still emerging strategy for improving sustainable aquaculture and aquaponic food production systems. Full article

Probiotics are widely studied as antibiotic alternatives in commercial aquaculture, yet their effects on fish maintained under long-term aquarium conditions remain poorly understood. This study addressed this gap by evaluating dietary Escherichia coli Nissle 1917 (EcN) supplementation on gut microbiota and inflammatory cytokine expression in hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) from a recirculating aquarium system. In this study, hybrid grouper were maintained in triplicate tanks under long-term aquarium environments, and fed a basal diet with 1 × 10⁸ CFU/g EcN (SS group) or a control diet (CS group) for 28 consecutive days. Based on 16S rRNA high-throughput sequencing and qPCR, the intestinal microbiota and expression levels of IL-4, TNF-α, and IL-1β were measured. At the phylum level, the relative abundance of Firmicutes increased from 15.63% (CS) to 66.70% (SS), while Proteobacteria decreased from 76.77% to 30.61%. At the genus level, Exiguobacterium became the dominant taxon in the SS group. Furthermore, EcN supplementation significantly upregulated IL-4 expression and downregulated TNF-α and IL-1β expression. EcN supplementation significantly altered gut microbiota composition, with marked changes in community structure and notable shifts in dominant taxa. Thus, this study provides one of the investigations into EcN-mediated restructuring of intestinal bacterial communities and modulation of host immune transcriptional responses in hybrid grouper maintained under controlled aquarium settings. These findings offer a foundation for designing microbiome-targeted interventions in captive marine fish systems. Full article

Silver pomfret (Pampus argenteus), a highly valued marine fish, faces challenges in aquaculture due to its sensitivity to environmental conditions. Recirculating aquaculture system (RAS) is likely to become a primary indoor cultivation method for silver pomfret in the future, so studying hydrodynamic characteristics at varying flow rates in silver pomfret RAS is crucial and has far-reaching implications for both aquaculture practices and economic returns. This study investigated the effects of water flow rates (low: 400 L/h, moderate: 600 L/h, high: 800 L/h) on the growth performance, nutritional metabolism, and gut microbiota of silver pomfret over an 8-week period. Transcriptome and 16S rRNA sequencing revealed that the moderate-flow-rate group exhibited superior growth performance, with enhanced expression of genes related to protein synthesis (HYOU1, PDIA6, ITGA11) and redox regulation (GLUL, DUSP1, GST). Additionally, the moderate flow rate promoted gut microbial diversity and stability, with higher abundances of fermentation- and chemoheterotrophy-related functions, suggesting improved nutrient metabolism. In contrast, high flow rates induced anaerobic metabolism, leading to lactate accumulation and reduced growth. These findings demonstrate that a moderate flow rate of 600 L/h optimizes silver pomfret aquaculture by enhancing growth, metabolic efficiency, and microbial health, providing a foundation for sustainable large-scale farming practices. Full article

The integration of diatom cultivation with aquaculture systems offers a promising strategy to simultaneously address nutrient-rich effluent discharge and the high costs of synthetic media. This study evaluates the growth performance, nutrient removal, CO₂ fixation, and fucoxanthin production of the marine diatom Thalassiosira sp. cultivated in three media: nitrified effluent from a recirculating aquaculture system (RAS; denoted as Aqua), synthetic F/2 medium, and a mixed medium (F/2 + Aqua, 1:1 v/v). The mixed medium demonstrated the best overall performance, indicating a synergistic effect between aquaculture-derived nutrients and targeted supplementation. After 8 days, biomass concentration reached 655 mg L⁻¹, representing a 30% and 317% increase compared with F/2 and Aqua, respectively, with a CO₂ fixation rate of 152.89 mg CO₂ L⁻¹ d⁻¹. This medium also achieved high nutrient removal efficiencies (93.67% nitrate and 97.94% phosphate) and enhanced fucoxanthin production (4.15 mg L⁻¹). In addition, biomass contained essential fatty acids, including arachidonic acid (7.12% of total fatty acid (TFA)) and eicosapentaenoic acid (7.58% TFA), supporting its suitability for aquaculture. Importantly, partial substitution of synthetic nutrients with RAS effluent reduced medium-input costs by approximately 62% while maintaining high productivity. Overall, this study demonstrates a resource-efficient, cost-effective, and sustainable approach for integrating wastewater treatment with high-value diatom biomass production, supporting circular aquaculture systems. Full article

The treatment of high-salinity, low-carbon marine aquaculture wastewater poses significant challenges for biological denitrification. This study systematically evaluated the performance of a polycaprolactone (PCL)-based aerobic denitrification biofilter under varying temperatures (15 °C and 25 °C) and PCL addition levels (282, 564, 846, 1128, and 1410 g). Optimal nitrogen removal, total nitrogen (TN) removal efficiency exceeding 92%, was achieved with 1128 g PCL at 15 °C (HRT 10 h) and 1410 g PCL at 25 °C (HRT 8 h), significantly outperforming the low-PCL baseline treatment. Microbial community analysis revealed that increased PCL dosage promoted the dominance of the hydrolytic genus Flavobacterium over Simplicispira, enhancing polymer degradation capacity and system stability. Metagenomic sequencing further elucidated the complete PCL degradation pathway, wherein hydrolysis products were oxidized to generate NADH and FADH₂, serving as electron donors for denitrification. Key functional genes (narG, nirK, nosZ) and enzymes associated with both PCL decomposition and nitrate reduction were significantly enriched in high-performance reactors (e.g., AT15H6, AT25H6, ET15H10, ET25H10), correlating strongly with observed nitrogen removal rates. By integrating reactor performance with microbial ecology and functional genetics, this work provides a comprehensive “material–microorganism–gene–performance” framework, offering both practical strategies and mechanistic insights for enhancing denitrification in saline aquaculture systems. Full article

Dulce (Palmaria palmata) is a high-value macroalga that is increasingly being cultivated, with strong potential for waste valorisation in nutrient-rich aquaculture systems (RASs). This study evaluated P. palmata growth in, and nutrient uptake from, commercial Atlantic salmon RAS effluent. A 12-week bench-scale experiment cultivated wild-collected P. palmata (average 10 g fresh weight, FW). These were grown in 1 L glass beakers at three effluent dilutions (25%, RAS25; 50%, RAS50; 100%, RAS100) and in seawater (SW) using 10 replicates. The water samples were analysed for ammonium nitrogen (NH₄-N), nitrate nitrogen (NO₃-N), and orthophosphate (PO₄-P) using a spectrophotometer. RAS25 and RAS50 exhibited 100% survival and maintained a dark red colour, with RAS50 achieving the highest specific growth rate (0.49 ± 0.13% day⁻¹), significantly higher than that of SW and RAS25. In contrast, RAS100 led to complete disintegration by 4–8 weeks with significant colour degradation. SW also exhibited reduced colour and 50% mortality by week 12. Sori’s presence was highest in RAS25/RAS50 (up to 80% at week 8 in RAS50), low in SW (10%), and absent in RAS100. The NH₄-N uptake was notably 3× higher than that of NO₃-N (0.16 vs. 0.05 mg g FW⁻¹ day⁻¹), without differences among the groups. The PO₄-P uptake was significantly higher for RAS50 (0.07 mg g FW⁻¹ day⁻¹) than for RAS100. P. palmata performed best in the diluted RAS effluents, as undiluted conditions led to acute tissue disintegration; the nitrogen and phosphorus uptake from the RAS effluents demonstrates significant potential for nutrient valorisation. Full article

Accurate monitoring of fish body length and mass is essential for evaluating growth status, optimizing feeding strategies, and supporting intelligent aquaculture management. However, conventional manual measurements are labor-intensive and may induce stress or injury due to repeated fish handling. To address these limitations, this study developed AquaFishNet, a binocular vision-based framework for non-contact underwater body length and mass estimation of Leiocassis longirostris. Underwater images were collected in a real recirculating aquaculture environment using a calibrated binocular camera system. AquaFishNet integrates lightweight fish body segmentation, stereo vision-based length estimation, and deep regression-based mass prediction. Experimental results showed that body length estimation errors were mostly within approximately ±2 cm, with relative errors generally below 8%. For body mass prediction, most relative errors were within approximately ±7%, and the model achieved an $R^2$ of 0.9851, RMSE of 18.38 g, and MAE of 12.92 g. These findings demonstrate that AquaFishNet provides an effective non-contact solution for fish growth monitoring and biomass estimation in precision aquaculture. Full article

The impact of a commercial microbial population (product name “RAS Right”) on the off-flavours geosmin and 2-methylisoborneol (2-MIB) in water and fish of a recirculating aquaculture system (RAS) for Nile tilapia production was studied over five months. The “RAS Right” product contains a microbiome that is reported to reduce geosmin. In the system that received “RAS Right”, geosmin ranged from 1.6 to 171.2 ng/L, while 2.4 to 89.3 ng/L occurred in the control RAS. After fluctuations in the first two months, water in the control RAS had lower geosmin concentrations (mean of 8.8 ng/L) than the treated RAS (mean of 16.6 ng/L). 2-MIB was low (<4.3 ng/L) or undetectable in both the control and treated systems. In the fish, geosmin varied from 112 to 3683 ng/kg, with the highest levels measured in the treated RAS during three of eight samplings. 2-MIB in the fish ranged from 11.6 to 136 ng/kg and peaked in the treated RAS in one sampling. The results indicate that “RAS Right” did not produce a significant reduction of geosmin or 2-MIB in water or fish. However, optimisation of the treatment with respect to dose or addition frequency may improve its effect, though this remains to be examined. Full article

Procambarus clarkii, a prominent aquaculture species, are mainly cultured through conventional modes: pond culture and rice–crayfish co-culture. In the present study, we proposed a novel industrial recirculating aquaculture system (RAS) for the culture of Procambarus clarkii. The nutritional quality of Procambarus clarkii under different culture modes was evaluated. The results indicated that industrial culture achieved optimal amino acid profiles and a higher level of flavor amino acids. Crayfish cultured in RAS also showed more balanced textures with moderate hardness and good springiness. Moreover, distinct crayfish metabolites were identified across different culture modes. The main differential metabolites include amino acids, peptides (and their analogs), organic acids and acyl carnitines. Industrial culture prioritized metabolites linked to flavor and rapid growth, while other culture modes enriched metabolites associated with ecological resilience and nutritional diversity. Overall, industrial culture displays great potential in improving the nutritional quality and regulating metabolic characteristics of red swamp crayfish. Full article

Turbot (Scophthalmus maximus) is a globally important species in both capture fisheries and aquaculture. With the development of the turbot farming industry in China and several European countries, enhancing its aquaculture eco-economic performance has become a key concern among stakeholders. Turbot is a major species in marine fish aquaculture in China. As the world’s leading producer of farmed turbot, the bioeconomic dynamics of this species under recirculating aquaculture systems (RASs) remain poorly understood, which hinders optimal resource allocation, green development, and industrial upgrading of the turbot farming sector. In this study, a bioeconomic model for turbot cultured in industrial RASs was developed based on empirical production data and published literature. The optimal harvesting strategies under the industrial RAS production mode were analyzed. The results indicated the following: (1) for a two-year grow-out cycle commencing with stocking at the beginning of the year, at a farm-gate price of 7.56 USD/kg, the maximum cumulative profit of 41,846.08 USD occurred at t = 22.69 months, while the maximum monthly average profit of 1937.65 USD/month occurred at t = 20.49 months. The optimal harvesting time for single-batch culture was t = 22.69 months, whereas for continuous culture, it was t = 20.49 months. (2) Extended analysis incorporating fish price variation revealed that higher market prices corresponded to later optimal harvesting times. (3) February to April was identified as the optimal stocking window. Based on the bioeconomic dynamics elucidated herein, this study provides a theoretical foundation for related research and proposes producer-oriented strategy recommendations for reference by relevant stakeholders. Full article

The red claw crayfish (Cherax quadricarinatus) is an economically important freshwater crustacean. This study comprehensively compared the physiological profiles of crayfish cultured in recirculating aquaculture systems (RAS) and rice–red claw crayfish co-culture systems (RRCS) over a 92-day experimental period (3 replicates per system; n = 15 crayfish sampled per group), focusing on growth performance, muscle quality, hepatopancreatic metabolomics, and intestinal microbiota. Results demonstrated that while RAS provided a significant growth advantage, RRCS exhibited superior muscle quality characterized by higher protein, lower moisture, and firmer texture. Regarding intestinal microecology, RAS induced a microbial shift toward the potentially pathogenic genus Vibrio, whereas RRCS promoted core symbionts like Candidatus Hepatoplasma. Multi-omics integration revealed that RRCS altered the intestinal microbiota and was associated with up-regulated hepatopancreatic pantothenate biosynthesis and TCA cycle pathways, alongside LysoPC-mediated membrane lipid remodeling. In conclusion, while RAS promotes rapid somatic growth, RRCS fosters a distinct intestinal microecology and hepatopancreatic metabolic profile that aligns with enhanced muscle quality. These findings provide a theoretical foundation for optimizing ecological aquaculture models. Full article

Proper configuration of aeration tubes is crucial for improving water quality and promoting the welfare and growth of cultured organisms in Recirculating Aquaculture Systems (RASs). To investigate the effects of aeration tube shapes (arc-shaped, disc-shaped, and linear-shaped) and positions (d = r, 1/2r) on performance, this study conducted experiments in a circular RAS tank. Methodologically, feed pellets were used to simulate solid waste, while ink was added to visualize the flow field, and mixing performance was quantitatively assessed using the spatial distribution uniformity. The results indicated that without aeration, the physical presence of the tubes affected waste collection but had minimal impact on water mixing. Under aeration conditions, placing tubes at d = 1/2r instead of d = r resulted in more efficient waste collection and improved water mixing. Waste collection performance was ranked as arc-shaped > disc-shaped > linear-shaped, whereas water mixing performance ranked linear-shaped > arc-shaped > disc-shaped. It is therefore recommended to place arc-shaped aeration tubes at d = 1/2r to achieve optimal overall performance. These findings provide valuable baseline insights into the selection and placement of aeration devices, offering preliminary practical guidance for aquaculture engineering. Full article

The recirculating aquaculture system (RAS) marks a significant shift in global aquaculture, transitioning to controlled, land-based production. This review highlights technological advancements that enable the treatment and reuse of over 90% of water, thereby enhancing water quality and production efficiency. These features position RAS as a cornerstone of sustainable seafood production. This review introduces the RAS Readiness Level (RRL) framework which is a novel, structured approach to assess the commercial maturity of emerging RAS technologies. Applying the RRL to six key technological domains (from digital AI systems to biological PHB recovery) reveals a pervasive pilot-scale purgatory where most innovations stagnate at RRL 4–6. It further addresses advanced processes such as membrane bioreactors, denitrification reactors, and the conversion of waste into valuable products. Furthermore, this review addresses persistent challenges, including high energy demand, economic viability, and the accumulation of pathogens. Finally, it focuses on the emergent integration of the Internet of Things (IoT) and artificial intelligence (AI), which are revolutionizing RAS management through data-driven optimization. By synthesizing current innovations, this review envisions a future of intelligent, closed-loop RAS where advanced IoT- and AI-driven technologies optimize water quality and feeding strategies to minimize ecological impact while enhancing sustainability and productivity. Full article

Recirculating aquaculture systems (RASs) improve water-use efficiency in fish production but generate nutrient-rich effluents requiring management. Integrating aquatic biomass cultivation into RASs offers a promising approach to nutrient recovery, CO₂ utilization, and biomass production. This study evaluates the technical and economic feasibility of integrating Wolffia globosa cultivation with RASs through process simulation and techno-economic analysis (TEA). A pilot-scale system in Thailand was modeled using SuperPro Designer, comparing static and suspended aeration cultivation. The suspended configuration required only ~10–12 m² for 28.80 m³, whereas static cultivation required 131 m² for 32.80 m³, corresponding to about a 12-fold reduction in land area. The suspended system achieved higher annual biomass production (1056 kg dry weight (DW) yr⁻¹) than the static system (690 kg DW yr⁻¹), corresponding to CO₂ fixation of ~1.50 and ~0.98 t CO₂ yr⁻¹, respectively. The static system achieved higher nutrient removal efficiencies (97% N and 99.66% P), while the suspended system showed lower removal (64% N and 65.30% P) but higher productivity. Economic analysis confirmed feasibility, with the suspended system achieving higher return on investment (17.56% vs. 12.89%) and a shorter payback period (5.70 vs. 7.76 years). These results demonstrate the potential of RAS–Wolffia integration as a circular approach for resource recovery and sustainable aquaculture. Full article

Schizopygopsis younghusbandi is an endemic and economically important fish in the Qinghai-Xizang Plateau, but its aquaculture is limited by harsh environmental conditions and incomplete understanding of host–microbiome–environment interactions. This study applied metagenomic sequencing to examine how different culture environments affect growth, water microbial communities, and gut microbiome network stability. Three-year-old juveniles (initial body weight 50.57 ± 1.88 g) were reared for 90 days in five systems: conventional pond (P), wetland (WL), concrete tank (G), river (R), and recirculating aquaculture system (RC). No significant differences in initial body weight or length were observed among groups (p > 0.05). Fish in the RC system achieved the highest final body weight, weight gain rate, and specific growth rate (p < 0.05), while survival rates were highest in the river and RC groups and lowest in ponds (p < 0.05). Microbial diversity and community composition differed significantly among culture modes, with bacterial and protozoan communities showing the strongest environmental responsiveness. Co-occurrence network analyses revealed that RC and G systems exhibited higher network complexity, density, and proportion of positive correlations, reflecting enhanced microbial interaction and ecological stability, whereas the WL system showed reduced network connectivity. Correlation analysis indicated that bacterial abundance was positively associated with total nitrogen, total phosphorus, and dissolved oxygen (p < 0.05), highlighting environmental regulation of microbial assemblages. Overall, the aquaculture environment shapes gut microbial networks, which closely relate to growth performance. Recirculating aquaculture systems can mitigate growth limitations in plateau fish by stabilizing the environment and reinforcing gut microbial communities, providing a sustainable strategy for high-altitude aquaculture development. Full article