Fish Aquaculture Research Articles

Fish resilience as an ethical issue.

Fish resilience can be understood as the capacity of fish to successfully respond to a challenge so that they are able to function and flourish in much the same way as they did prior to the occurrence of the challenge. Resilience is a function not only of individual fish, but also of a whole fish population. Enhancing the resilience of fish requires both adapting the robustness of the animals and adapting the (production) environment to the specific needs of the fish. Rather than a mere biological capacity of fish, resilience also comes with ethical questions. These questions occur at four levels. First, in practice resilience often comes with a "rhetoric" of optimalization. The view that aquaculture that strives for resilient fish is good for both fish welfare and production is inherently normative. It assumes a 'win-win situation', but thereby makes certain normative assumptions. Second, especially when the win-win situation is not achievable, resilience means making trade-offs between preferred responses to challenges from the perspective of individual animals and groups or between individual housing and larger aquaculture systems. Third, the discussions on resilience and fish demonstrate the need to move beyond an animal welfare framework when discussing the treatment of fish in aquaculture. Recently, animal ethics has seen a turn towards centering animals' own agency. This means that we should not only focus on improving animal welfare, but also on asking what the animals themselves want and how they can be given more control over their situation. This may also impact the definition of resilience and how it is made operational. Finally, the use of the concept of resilience may reveal a certain moral outlook with regard to fish. On the one hand, resilience is portrayed as a positive characteristic of animals that enables improvement of the quality of life of fish. At the same time, it raises the question of how far we should stretch the "manufacturability" of fish. When we physically adapt animals so that they can cope with difficult circumstances we may be stretching moral boundaries. For example, this raises the objection that we are instrumentalizing animals. In this article, we reflect on these types of ethical issues and aim to show that the ethical dimensions of resilience need to be taken into account by professionals in aquaculture in order to make resilience operational and to contribute to a responsible interaction with fish in aquaculture.

The application of plasmid DNA constructs encoding antiviral proteins as potential therapeutics against viral infections in salmonid aquaculture

Treatments to control infectious diseases in aquacultured fish commonly focus on the use of antibiotics (which are ineffective against viruses) and inorganic disinfectants. Currently, antiviral treatments are not available for use in aquaculture. The use of plasmid vectors to overexpress antiviral proteins in fish has been reported, with positive results against viral infections. The aim of this work was to overexpress the antiviral proteins interferon-induced protein with tetratricopeptide repeats 5 (IFIT5) and natural killer enhancing factor (NKEF) using plasmid vectors (pIFIT5 and pNKEF) as novel therapeutic agents against viral infections. The antiviral activity of pIFIT5 against viral hemorrhagic septicemia virus (VHSV) and infectious pancreatic necrosis virus (IPNV) was evaluated in vitro in epithelioma papulosum cyprinid and Chinook salmon embryo cell lines. Moreover, pNKEF antiviral activity against IPNV was also evaluated. Results showed that pIFIT5 had antiviral activity against both viruses, but pNKEF did not protect against IPNV. In addition, we evaluated the use of pIFIT5 and pNKEF constructs as therapeutics in rainbow trout. Biodistribution assays demonstrated systemic distribution of the IFIT5-TFP1 and NKEF-TFP1 proteins in rainbow trout injected with the plasmids, and pIFIT5 and pNKEF triggered an immune response in the injected fish. In a pilot study, we evaluated the level of protection conferred by pIFIT5 and pNKEF against VHSV in rainbow trout, and we observed 10 % survival for pIFIT5 compared to pTFP. Together, these results suggest the potential of pIFIT5 as therapeutic agent in aquaculture.

Antibiotic resistance and mitigation using One Health lens in aquaculture of Northern Nigeria.

A cross-sectional study was conducted to assess antibiotic usage, residues, resistance and drivers of their emergence in fish aquaculture in Northern Nigeria between 2019 and 2020. A structured questionnaire was administered to 151 randomly selected farmers. Fish, column and wastewater samples were analysed with enzyme link immunosorbent assay (ELISA) for residue detection and quantification. We performed descriptive and analytic statistical analyses. All selected farmers participated, 78.1% used antibiotics in ponds. Majority (77.1%) of the farmers did not know what antibiotic misuse entailed and 73.3% mentioned that antibiotic misuse and overuse cannot predispose to residues and resistance. The most frequently used antibiotics were tetracyclines (TCs) (99.2%). Significant risk routes for residue and resistance spread were: contaminated fish and its products ingestion, direct contact with fish and fomites contaminated as well as water and aerosols contaminated in the pond environment. Significant social and cultural that influenced residue and resistance development include antibiotics misuse/overuse (Odds Ratio [OR] = 3.8; 95% confidence interval [CI]: 1.62-8.74) as well as poor education and expertise of the farmers (OR = 2.9; 95% CI: 1.24-6.94). The mean TCs residues level in column and wastewater was 123.6 ± 18.2 μg/kg-1. Poor knowledge and attitudes regarding antibiotic usage were identified. Adequate antibiotic stewardship should be promoted through farmers' education. Identified social and cultural factors can be mitigated through the 'One Health' approach.

Economic Impact of Heavy Metals Accumulation in Aquacultured Tilapia Fish in Egypt

Economic Impact of Heavy Metals Accumulation in Aquacultured Tilapia Fish in Egypt

Reproductive performance of lumpfish (Cyclopterus lumpus, L. 1758) females: Effects of integrated photoperiod and temperature manipulations on sexual maturation and spawning.

A successful control of sexual maturation is crucial for year-round production of lumpfish juveniles destined as cleaner fish in Atlantic salmon aquaculture. This study investigated the combined effects of photoperiod and temperature manipulations on sexual maturation and spawning in lumpfish females. Lumpfish juveniles were exposed to simulated natural and nine-month compressed annual photoperiods, with subsequent temperature elevation. Body weight (BW), condition factor (K), gonadosomatic index (GSI), ovarian development, plasma levels of 17β-estradiol (E2), testosterone (T) and 11-ketotestosterone (11-KT), and spawning were assessed. Compressing the natural photoperiod caused a clear increase and decrease in GSI, T, 11-KT and E2 towards and during the spawning period. Before the temperature elevation, GSI, T, 11-KT, E2 and ovarian development were advanced in the compressed photoperiod. After the temperature elevation, GSI, T, 11-KT and E2 fluctuated more in the compressed photoperiod, while in the natural photoperiod, E2 declined, and GSI, T and 11-KT increased. Spawning was advanced by 1 month in the compressed photoperiod compared to the natural photoperiod. Temperature elevation led to higher levels, earlier peaks and declines of T, 11-KT or E2 in both photoperiods, and advanced spawning by 1.5 months in the compressed photoperiod compared to the natural photoperiod. Temperature elevation also led to increased ovulation recruitment and increased cumulative weight of spawned eggs in the natural photoperiod. Compressing the natural photoperiod and elevating temperature can thus advance sexual maturation and spawning in lumpfish females. Due to the lower amounts of spawned egg weights in the high temperature compressed photoperiod, further studies on effects of photoperiod and timing of temperature manipulations on spawning, fecundity and egg quality could optimize the photothermal manipulations on lumpfish broodstock.

Integrated miRNA-mRNA analysis uncovers immediate-early response to salinity stress in gill-derived cell line of Gymnocypris przewalskii

Salinity adaptation is an important issue in aquaculture. Understanding the immediate-early response to salinity stress helps in comprehending this process. In vitro experiments using cell lines can explain cell-independent reactions without the involvement of hormones in vivo. In this study, salinity stress experiments were conducted using cell line derived from the gills of Gymnocypris przewalskii (GPG cell line) to isolate immediate-early response-related genes and miRNAs using transcriptomics, followed by bioinformatics analysis. The results showed that intracellular free Ca2+ appeared to be a key factor in cell sensing and initiating downstream cell signaling in response to external salinity. Additionally, cell apoptosis was the most common feature of salinity stress, with multiple signaling pathways involved in salinity-induced cell apoptosis. Furthermore, MiRNAs played a crucial role in the rapid response to salinity stress by selectively inhibiting the expression of specific genes. Additionally, for the first time in the G. przewalskii genome, Tf2 and TY3 families of transposons were found to have responsive roles to the external salinity stress. This study contributes to a better understanding of osmotic sensing in G. przewalskii and provides theoretical assistance for improving salinity adaptation in aquaculture fish species.

Use of water bodies for fish farming: land and legal aspects

The article examines the features of using water bodies for fish farming from a land and legal perspective. Based on an analysis of current Ukrainian legislation, the author concludes that fish farming and aquaculture are synonymous terms. It is emphasized that for proper legal regulation of the use of water bodies for fish farming, the connection of these bodies to the land plots on which they are located must be considered. It is argued that the legal regulation of the use of water bodies for fish farming stems from the specific nature of these objects and their connection with other resources. The article thoroughly substantiates that regulating the use of land or water resources separately cannot be effective, as any economic activity related to one of these objects inevitably impacts the other. An analysis of the legal provisions in the Land Code of Ukraine, the Water Code of Ukraine, and the Law of Ukraine «On Aquaculture» regarding the regulation of fish farming on water fund land plots with water bodies is provided. The author notes that the norms concerning the use of water bodies for fish farming are reflected not only in land and water legislation but also in agricultural legislation. Specifically, according to Article 1 of the Law of Ukraine «On Aquaculture», fish farming is defined as a type of agricultural activity, and agricultural activities are regulated by agricultural law norms. The author argues that in the process of legal regulation of relations related to fish farming, it is necessary to consider not only land and water law but also the norms of agricultural law, which encompass a broader range of legal relations connected with agricultural activities. This makes legal regulation more comprehensive and balanced, taking into account all aspects of land use under water bodies for fish farming. The practical application of such a comprehensive approach ensures effective use of natural resources and helps avoid legal conflicts.

Searching for sea lice: surveillance to assess environmental infection pressures to model and inform sea lice infestation management

The expansion and development of sustainable salmon aquaculture requires research, innovation and, where necessary, regulation to manage environmental impacts. Sea lice are a key concern for marine salmonid fish aquaculture as these parasites adversely affect farmed and wild salmonids. Reducing the risk of harmful infestation levels requires appropriate data to support modelling and inform adaptive management processes. Throughout their life cycle, sea lice occur as either planktonic larvae or as ectoparasites on farmed, wild or sentinel fish host populations. Limited resources require surveillance methodologies and strategies for these stages to be optimized to obtain data that meet the specific needs of control. In this review we assess the different surveillance strategies available to inform the appropriate management of sea lice impacts on wild salmonids. We advocate modelling as the most effective way to use surveillance data, with subsequent model improvements informed by the continued input of collected data. A feedback loop is proposed of identifying/collecting empirical data to improve models, which in turn will direct more focused surveillance for future data collection and so drive adaptive management processes. In the future, surveillance monitoring, as part of an adaptive management regime in Scotland, should build on existing links between stakeholders and policy makers, and use both models and data to help the sustainable development of the aquaculture industry.

Identification of the effects of hypoxia on the liver tissues of Nile tilapia Oreochromis Niloticus

BackgroundHypoxia stress resulted in mortality during the fish aquaculture program, affecting the sustainable development of the aquaculture industry. The Egyptian strain of O. niloticus showed a strong ability to hypoxia. In this study, a Nile tilapia strain that was kept and selected for 45 years by the author’s team was used to elucidate the mechanism of the hypoxia response in the liver, including the identification of metabolic pathways and genes, involved in the hypoxia response of this strain.ResultsThe effects of hypoxia stress were detected at 0-hour, 6-hour, and 72-hour time points (0 h, 6 h, 72 h) on tilapia liver at 1 mg/L dissolved oxygen conditions. The blood triglyceride, blood glucose and cholesterol values exhibited significantly different change trends, but the hemoglobin content showed no significant differences between 0 h, 6 h and 72 h (P > 0.05). The activities of catalase (CAT), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), lactate dehydrogenase (LDH), and acid phosphatase (ACP) in the liver tissue gradually increased at 0 h, 6 h and 72 h (P < 0.05). Histological analyses revealed structural changes in intracellular lipid droplets, nuclear migration and dissolution, and cell vacuolization in liver tissues. Six pathways were identified as the main enriched metabolic pathways according to the transcriptome profiling analysis, which were protein processing in endoplasmic reticulum, steroid biosynthesis, peroxisome, PPAR signaling pathway, glycolysis/gluconeogenesis and Insulin signaling pathway. The expressions of the important differentially expressed genes were verified by qPCR analysis, including erola, LOC100692144, sqle, cratb, pipox, cpt1a2b, hik and acss2l, ehhadh, prkcz, fasn and plaa, which showed the same expressions trends as those of RNA-Seq.ConclusionsThe Nile tilapia strain improves the abilities of hypoxia response through energy metabolism. Antioxidant enzyme measurements in the liver indicate that these five antioxidant enzymes play important roles in protecting the body from hypoxic damage. The histological changes in liver cells indicate that the damage caused by hypoxia stress. The immune-related metabolic pathways and energy metabolism-related pathways were obtained by transcriptome profiling, and these metabolic pathways and the differentially expressed genes selected from these metabolic pathways may be involved in the mechanism of hypoxia tolerance in this strain. These findings provide a better understanding of the hypoxia response mechanism of fish, and represent a useful resource for the genetic breeding of O. niloticus.

Bacterial diseases in Siniperca chuatsi: status and therapeutic strategies.

Mandarin fish (Siniperca chuatsi) is a prominent freshwater species with significant economic value in China, while disease poses a major hindrance to the advancement of mandarin fish aquaculture. To date, the understanding of the prevention and management of bacterial disease in mandarin fish remains incomplete. Therefore, there is a need for more comprehensive insights into the preventive and curative strategies to address these bacterial infections. In this review, we summarize the information pertaining to the predominant bacterial pathogens such as Aeromonas spp., Flavobacterium columnare, Edwardsiella tarda, Streptococcus uberis and Vibrio cholerae in the mandarin fish aquaculture, and point out the current strategies for diagnosis and combating these bacterial pathogens, as well as deliberate on the prospective alternative treatments such as vaccines, herbal remedies, and phage therapy for the prevention and control of these bacterial diseases. Furthermore, we also highlights the importance to implement an integrated bacterial disease management (IBDM) approach for the prevention and control of these pathogenic bacteria in aquaculture.

Comparative Study of Fatty Acid Composition of Muscles of Atlantic Cod (Gadus morhua Linnaeus, 1758) with Natural Diet and Feeding near Salmon Farms

Coastal aquaculture and local fisheries interact in shared marine environments, influencing each other synergistically and/or antagonistically. Salmon farming, notably with open-net sea cages along the Norwegian coast, attracts wild fish due to increased food availability from uneaten feed, but it also exposes wild fish to farm emissions like waste and toxic chemicals (de-lice treatments, antifouling and medical agents). The attraction behaviour of wild fish can impact fatty acid composition in fish tissues, influenced by the high terrestrial fat content in salmon aquafeed. We study how the Atlantic cod, aggregating around salmon farms in a subarctic fjord in Northern Norway, can be affected, potentially altering their natural diet and fatty acid profiles. Our study compares the muscle-tissue fatty acid compositions of cod caught near aquaculture facilities (impact) versus fish caught in neighbouring fjords (control), and we hypothesise decreased omega-3 fatty acids near farms. The analysis revealed no significant differences in the fatty acid concentrations or categories between the impacted and control fish, challenging our initial expectations. However, differences were found for C18:1(n9)t (elaidic acid), with a higher value in the impacted fish. These findings suggest that salmon farming’s influence on cod’s fatty acid profiles in the flesh (i.e., relevant for the nutritional quality of the fillets that consumers eat) may be limited or minimal despite their aggregative behaviours around farms. The threshold levels of salmon feed consumed by wild cod before it affects the quality and survival of, e.g., sperm or other life stages, are not known and require new investigations. This study underscores the complexity of interactions between aquaculture and wild fisheries, impacting both ecological dynamics and consumer perspectives on seafood quality and health benefits.

Factors Affecting Yeast Digestibility and Immunostimulation in Aquatic Animals.

The aquafeed industry increasingly relies on using sustainable and appropriate protein sources to ensure the long-term sustainability and financial viability of intensive aquaculture. Yeast has emerged as a viable substitute protein source in the aquaculture sector due to its potential as a nutritional supplement. A substantial body of evidence exists to suggest that yeast has the potential to act as an effective immune-stimulating agent for a range of aquaculture fish species. Furthermore, the incorporation of yeast supplements and feed additives has the potential to bolster disease prevention, development, and production within the aquaculture sector. Except for methionine, lysine, arginine, and phenylalanine, which are typically the limiting essential amino acids in various fish species, the various yeast species exhibit amino acid profiles that are advantageous when compared to fishmeal. The present review considers the potential nutritional suitability of several yeast species for fish, with particular attention to the various applications of yeast in aquaculture nutrition. The findings of this study indicate that the inclusion of yeast in the diet resulted in the most favorable outcomes, with improvements observed in the overall health, growth performance, and nutritional condition of the fish. Digestibility, a key factor in sustainable feed development, is discussed in special detail. Additionally, this review addresses the utilization of yeast as an immunostimulating agent for fish and its digestion in fish. Furthermore, the research emphasizes the necessity of large-scale production of yeast as a substitute for fishmeal in aquaculture.

Smartphone apps pertaining to aquaculture sector in Bangladesh: Current status and future potentials

In recent years, the aquaculture sector in Bangladesh has experienced significant technological advancements, notably the adoption of smartphone applications. This empirical study evaluates the current status of smartphone apps available in the aquaculture industry of the country using data obtained from the internet and field surveys. The study identified 41 smartphone apps currently used in the sector, where 58.53 % are related to pond-based aquaculture, 14.63 % are designed for biofloc system, 4.87 % pertain to cage aquaculture and 4.87 % marketing-aided corporate-related apps, 9.75 % focus on disease and treatment-related, and 7.31 % fall into miscellaneous categories. The “Poultry Animals and Aqua Index (PAAI)" app, which addresses aquaculture pharmaceutical inputs and fish disease treatment guidelines, emerged as the most downloaded app in this domain. Pearson correlation analysis indicated that app size or user ratings did not influence app downloads. The study also found that approximately 57.66 % of fish farmers are aware of these smartphone apps. Private fisheries professionals were the main driving forces behind the use of these apps, accounting for 52 % of the information spread. Despite mixed levels of satisfaction among farmers, about 25 % expressed a positive experience. Most of the farmers (57.66 %) acknowledged the awareness and beneficial impacts of using these apps in aquaculture. This study enhances the understanding of smartphone apps usage in Bangladesh to promote the aquaculture industry, highlighting its potential to promote industry growth, alleviate poverty, and contribute to economic development.

Fish Species Assemblages and Diversity in Water Body Infested by Alien Species

Human is one of the mediators for non-native species invasion, especially in the aquatic ecosystem. Aquaculture and sport fishing activities are the main reasons for non-native fish introduction, especially in man-made habitats. In the present study, we determined the fish community between the invaded as opposed to pristine ecosystems in north Terengganu, Malaysia. The primary data was collected using hook and line, hand-held push net, cast net and gills net while secondary data were also utilised from published and unpublished data. The fish general information including functional traits and prey-predator relationship were obtained from literature and reliable online resources. The data were used to construct hypothetical diagrams and analyzed using taxonomic distinctness index. The fish community between the two habitats differ significantly in which the non-native fish invaded habitat has much lesser fish species richness than that of the pristine habitat. Taxonomic diversity between the two habitats also was markedly different. The non-native Cichla ocellaris added predation pressure to fish community in the lacustrine habitat as the apex predator and were proven to feed on the native fish fauna in the lake. We discuss the community structure in both habitats and explore the further impact of invasion by this invasive alien species on the native fish species. We conclude that the presence of Cichla ocellaris amplify pressure to native fish community in the man-made lake.

Aroma-active compounds in Russian sturgeon (Acipenser gueldenstaedtii) raised in recirculating aquaculture systems

The rearing system affects the nutritional and sensorial qualities of the Russian sturgeon (Acipenser gueldenstaedtii), a niche yet commercially valuable aquaculture species for caviar production. In the present work, we aimed to comprehensively characterize the odorant composition of fillets from Russian sturgeon raised in a recirculating aquaculture system (RAS) and discuss potential sources and formation pathways. A total of 114 odorants were detected through the application of combined sensory-instrumental analyses, of which 88 were successfully identified and 20 substances were found to be among the most potent odor constituents. The most dominant odorants were assigned to several specific substance classes, including aldehydes, alcohols, terpenes, ketones, organic acids, lactones, heterocycles, aromatic hydrocarbons, and sulfur-containing aldehydes. The compounds (E)-hex-2-enal, (Z)-hept-4-enal, cuminaldehyde, non-3-yn-1-ol, 3-carene, 2-methylisoborneol, geosmin, oct-1-en-3-one, nonan-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, hexanoic acid, γ-crotonolactone, γ-octalactone, 2-acetyl-thiazoline, methional, and (2E,4Z,7Z)-trideca-2,4,7-trienal had high flavor dilution factors and are described for the first time as potent odor-active compounds associated with the Russian sturgeon. Overall, oct-1-en-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, 2-methylisoborneol, and hexanoic acid had the highest flavor dilution factors. This study offers a basis for future development in the sturgeon RAS industry from the perspective of flavor characterization by providing deep insights into the fundamental composition and origins of the complex world of aquaculture fish aroma.

Barley as a production platform for oral vaccines in sustainable fish aquaculture

Vaccination is the most effective measure to prevent disease outbreaks in fish aquaculture, with oral vaccine administration emerging as the most practical approach. However, oral vaccines face a notable limitation due to insufficient stimulation of the complex gut-associated lymphoid tissue caused by factors such as vaccine degradation, poor absorption, and recognition by the immune cells. An innovative solution to these limitations lies in the plant-based production of recombinant vaccines. Plant cells enable the production and targeted storage of recombinant vaccines in specific cell organelles which ensure superior protection from degradation and contain natural compounds acting as adjuvants. Our study explores the potential of barley (Hordeum vulgare), a globally significant cereal crop, for producing orally administered subunit vaccines against viral infections affecting economically important fish species in the Salmonidae and Cyprinidae families. Through Agrobacterium-mediated transformation of immature barley embryos, we have generated homozygous T2 generation of transgenic barley expressing recombinant antigens of spring viremia of carp virus and infectious salmon anaemia virus. The expression of these plant-based recombinant vaccines was confirmed by immunodetection, which was supported by fluorescence observation, specifically in the seed endosperm. The antigenicity of transgenic plant material containing recombinant antigens was evaluated using an intubation model of common carp (Cyprinus carpio), revealing a substantial upregulation of the immunoglobulin transcripts in both systemic and mucosal tissues over a period of 28 days following a single dose of transgenic antigens. Collectively, these results underscore the potential of barley-based recombinant vaccines for disease prevention in fish aquaculture.

Leader RNA facilitates snakehead vesiculovirus (SHVV) replication by interacting with CSDE1 and hnRNP A3

Leader RNAs are viral small non-coding RNAs that has been proved to play important roles in viral replication. Snakehead vesiculovirus (SHVV) is an aquatic virus that has caused huge economic loss in Chinese snakehead fish aquaculture industry. It has been proved that SHVV would generate leader RNA during the process of infection, and leader RNA could interact with viral nucleoprotein to promote viral replication. In this study, we identified that leader RNA could also interact with cellular protein Cold Shock Domain containing E1 (CSDE1) and heterogeneous nuclear ribonucleoproteins A3 (hnRNP A3). Further investigation reveals that overexpression of CSDE1 and hnRNP A3 facilitated SHVV replication. Downregulation of CSDE1 and hnRNP A3 by siRNA inhibited SHVV replication. This study provided a new sight into understand the mechanism of SHVV replication, and a potential anti-SHVV target for drug research.

Dietary overlap of invasive cyprinids and common carp in fishponds of Central Europe

Freshwater fishponds are an important part of the global aquaculture fish production, but they also are a source of invasive species with potentially negative impacts on pond ecosystems. In this study, we investigated dietary competition between common carp (Cyprinus carpio) and two invasive cyprinids, Pseudorasbora parva and Carassius gibelio, in fishponds of Central Europe. Using δ13C and δ15N stable isotopes analysis, we evaluated the extent of isotopic niche overlaps and the utilization of dietary sources by these species in fishponds that differ in the intensity of fish production. The isotopic niche of C. carpio and the invasive cyprinids overlap more in ponds with intensive (south-eastern Czechia) and semi-intensive (northern Austria) fish production then in ponds with low intensity production (eastern Slovakia). Our results also suggest that both invasive species opportunistically adjust their diet to their gape size and that they predominantly assimilate dietary energy from zooplankton and macroinvertebrates rather than from primary producers and detritus. Our study highlights the high potential of these invasive cyprinids to compete with C. carpio in fishponds of Central Europe.

Development of Welfare Protocols at Slaughter in Farmed Fish.

The study investigated fish welfare at slaughter. Killing animals may induce suffering to the animals even under the best available technical conditions. Moreover, fish have different physiological characteristics and are slaughtered differently from terrestrial animals. The use of commercially available methods exposes farmed fish to pain and suffering during slaughter, which could lead to acute stress and post mortem changes in fish quality. The study aimed to discuss (i) the current knowledge and knowledge gaps on fish welfare related to stunning and killing methods; (ii) the variables that affect the post mortem changes in fish meat, and (iii) the indicators of welfare during slaughter. Application of welfare protocols at slaughter improves fish welfare. Specific protocols for fish are not provided in EC Regulation 1099/2009 on animal protection at killing. Detailed guidelines in the fish welfare assessment may allow the development of specific fish legislation. Developing humane technologies might have important effects on fish quality, consumer perception and aquaculture economics.

A smart monitoring and observation framework for aquaponics ecosystem

Aquaponics is a sustainable and efficient agricultural system that integrates aquaculture with agriculture. This system integrates Internet of Things (IoT) technology in aquaponics systems with the potential to change sustainable agriculture by combining farming of fish (aquaculture) and soilless cultivation of plants (hydroponics) into a single, efficient ecosystem. This paper explores the design and development of a smart aquaponics system that allows aquaponic farming at commercial scale feasible, leveraging IoT to continuously gather data through various sensors, monitor environmental conditions, and automate control processes. The proposed system architecture is based on a three-tier model, ensuring scalability and maintainability. The proposed system consists of a three-layer architecture: the Perception Layer for measuring different environmental factors and controlling them, the Network Layer for data transmission, and the Application Layer for data storage, manipulation, and user interaction. The key components include sensors for monitoring pH, humidity, temperature, sunlight, oxygen levels, and water proximity; devices such as lights, water pumps, fans, and oxygen pumps for environmental control; and an ESP8266 microcontroller for system management. The system's software is developed using C# DOT NET CORE 8.0, React, MySQL, C, and Arduino. The system allows users the ability to maintain optimal conditions for fish and plant growth, notify users of irregularities, and allow remote control through a web application, proving it to be an intelligent, flexible, low-cost, and stable solution for large-scale aquaponics.