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With the rapid growth of inland aquaculture worldwide, side effects such as the discharge of nutrients and antibiotics pose a threat to the global environments. A sustainable future for aquaculture requires an effective management system, including the early detection of disease through the monitoring of specific biomarkers in aquaculture tanks. To this end, we investigated whether fish feces in aquaculture tanks could be used for non-invasive health monitoring using ayu ( Plecoglossus altivelis ) infected with Flavobacterium psychrophilum , which causes bacterial cold-water disease worldwide. Feces that were subsequently produced in the tanks were used for metagenomic and metabolomic analyses. The relative abundances of the genera Cypionkella (0.6% ± 1.0%, 0.1% ± 0.2%), Klebsiella (11.2% ± 10.0%, 6.2% ± 5.9%), and F. psychrophilum (0.5% ± 1.0%, 0.0% ± 0.0%) were significantly higher in the feces of the infection challenge test tanks than in those of the control tanks. The abundances of cortisol, glucose, and acetate in the feces of the infection challenge test tanks were 2.4, 2.4, and 1.3 times higher, respectively, than those of the control tanks. Metagenome analysis suggested that acetate was produced by microbes such as Cypionkella . The abundances of indicated microbes or metabolites increased after day 4 of infection at the earliest, and were thus considered possible biomarkers. Our results suggest that feces produced in aquaculture tanks can potentially be used for non-invasive and holistic monitoring of fish diseases in aquaculture systems., Importance: The aquaculture industry is rapidly growing, yet sustainability remains a challenge. One crucial task is to reduce losses due to diseases. Monitoring fish health and detecting diseases early are key to establishing sustainable aquaculture. Using metagenomic and metabolomic analyses, we found that feces of ayu infected with Flavobacterium psychrophilum contain various specific biomarkers that increased 4 days post-challenge, at the earliest. Our findings are the first step in establishing a novel, non-invasive, and holistic monitoring method for fish diseases in aquaculture systems, especially in ayu, which is an important freshwater fish species in Asia, promoting a sustainable future., Competing Interests: The authors declare no conflict of interest.

Disease poses a significant threat to aquaculture. While there are a number of factors contributing to pathogen transmission risk, movement of live fish is considered the most important. Understanding live fish movement patterns for different aquaculture sectors is therefore crucial to predicting disease occurrence and necessary for the development of effective, risk-based biosecurity, surveillance and containment policies. However, despite this, our understanding of live movement patterns of key aquaculture species, namely salmonids and cyprinids, within England and Wales remains limited. In this study, networks reflecting live fish movements associated with the cyprinid and salmonid sectors in England and Wales were constructed. The structure, composition and key attributes of each network were examined and compared to provide insight into the nature of trading patterns and connectedness, as well as highlight sites at a high risk of spreading disease. Connectivity at both site and catchment level was considered to facilitate understanding at different resolutions, providing further insight into disease outbreaks, with industry wide implications. The study highlighted that connectivity through live fish movements was extensive for both industries. The salmonid and cyprinid networks comprised 2533 and 3645 nodes, with a network density of 5.81 × 10 -4 and 4.2 × 10 -4 , respectively. The maximum network reach of 2392 in the salmonid network was higher, both in absolute terms and as a proportion of the overall network, compared to maximum network reach of 2085 in the cyprinid network. However, in contrast, the number of sites in the cyprinid network with a network reach greater than one was 513, compared to 171 in the salmonid network. Patterns of connectivity indicated potential for more frequent yet smaller scale disease outbreaks in the cyprinid industry and less frequent but larger scale outbreaks in the salmonid industry. Further, high connectivity between river catchments within both networks was shown, posing challenges for zoning at the catchment level for the purpose of disease management. In addition to providing insight into pathogen transmission and epidemic potential within the salmonid and cyprinid networks, the study highlights the utility of network analysis, and the value of accessible, accurate live fish movement data in this context. The application of outputs from this study, and network analysis methodology, to inform future disease surveillance and control policies, both within England and Wales and more broadly, is discussed., (Copyright © 2020. Published by Elsevier B.V.)

The marine leech, Zeylanicobdella arugamensis, is a major threat to aquaculture in grouper-producing countries including Indonesia. This study aimed at investigating prevalence, intensity and histopathology of the ectoparasite in humpback and hybrid groupers cultured in different rearing systems. A total of 260 groupers (60 humpback groupers and 200 hybrid groupers) were used for samples. The marine leech was observed on skin, fins, gills and mouth, followed by histopathological assay on the skin tissue. The results showed that prevalence of the leech in both groupers was higher when they were cultured in the floating net cages compared with the hatchery, p < .05. Furthermore, humpback grouper had a higher prevalence than hybrid grouper when they were cultured in a similar system, p < .05. Meanwhile, there was no significant difference in intensity between the two groupers, p > .05. Within the hybrid groupers, the highest prevalence was obtained from hybrid groupers reared in the earthen ponds. Histopathological studies showed that the infected groupers exhibited inflammation, congestion and erosion of the epidermis layer. Hybrid grouper had more severe histopathological lesions in the skin tissues. These results suggested that species and type of aquaculture system had significantly determined the prevalence, intensity and severity of lesion in Z. arugamensis infestation., (© 2020 John Wiley & Sons Ltd.)

Edwardsiella piscicida, a Gram-negative, facultative aerobic pathogen belonging to the Enterobacteriaceae family, is the etiological agent of edwardsiellosis in fish and a significant problem in global aquaculture. E. piscicida has been reported from a broad geographical range and has been isolated from more than 20 fish host species to date, but this is likely to be an underestimation, because misidentification of E. piscicida as other species within the genus remains to be resolved. Common clinical signs associated with edwardsiellosis include, but are not limited to, exophthalmia, haemorrhages of the skin and in several internal organs, mild to moderate dermal ulcerations, abdominal distension, discoloration in the fish surface, and erratic swimming. Many antibiotics are currently effective against E. piscicida, although legal restrictions and the cost of medicated feeds have encouraged significant research investment in vaccination for the management of edwardsiellosis in commercial aquaculture. Here we summarise the current understanding of E. piscicida and highlight the difficulties with species assignment and the need for further research on epidemiology and strain variability.

Freshwater fish farming contributes to more than two-thirds of global aquaculture production. Parasitic ciliates are one of the largest causes of production loss in freshwater farmed fishes, with species from the genus Chilodonella being particularly problematic. While Chilodonella spp. include 'free-living' fauna, some species are involved in mortality events of fish, particularly in high-density aquaculture. Indeed, chilodonellosis causes major productivity losses in over 16 species of farmed freshwater fishes in more than 14 countries. Traditionally, Chilodonella species are identified based on morphological features; however, the genus comprises yet uncharacterized cryptic species, which indicates the necessity for molecular diagnostic methods. This review synthesizes current knowledge on the biology, ecology and geographic distribution of harmful Chilodonella spp. and examines pathological signs, diagnostic methods and treatments. Recent advances in molecular diagnostics and the ability to culture Chilodonella spp. in vitro will enable the development of preventative management practices and sustained freshwater fish aquaculture production., (© 2016 John Wiley & Sons Ltd.)

Simple Summary: In this study, environmental DNA technology, 16S rRNA gene sequencing, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were employed to investigate the relationships between Tetrahymena pyriformis, bacteria, and guppies under varying temperature and pH conditions. The abundance of T. pyriformis in water, the relative abundance of bacterial species, and histopathological observations were studied. Results of this study showed that several bacteria were related to T. pyriformis, and environmental factors affected the interaction between bacteria and T. pyriformis. In the aquaculture system of ornamental fish, the interaction between bacterial microbiota and ciliate protozoa can prevent or promote disease outbreaks, and different physicochemical conditions will affect the relationships between them. We investigated the interaction between bacterial microbiota and the parasite Tetrahymena pyriformis when infecting Poecilia reticulata (guppy) under different physicochemical conditions. The abundance of T. pyriformis in water, the relative abundance of bacterial species, and histopathological observation were studied or monitored using environmental DNA (eDNA) extraction technology, the qPCR method, and 16s rRNA sequencing, respectively. The morphological identification and phylogenetic analysis of T. pyriformis were carried out. The infected guppy tissue was also stained by the hematoxylin and eosin methods. The results showed: (1) the bacterial communities of water samples were mainly composed of species assigned to Proteobacteria and Bacteroidetes, and Tabrizicola and Puniceicoccaceae were positively correlated with fish mortality, T. pyriformis abundance, and temperature. (2) Arcicella and Methyloversatilis universalis with different correlations between ciliates appeared in different treatment groups, the result of which proved that environmental factors affected the interaction between bacteria and T. pyriformis. (3) Lower temperatures and a higher pH were more beneficial for preventing disease outbreaks. [ABSTRACT FROM AUTHOR]

Aquaculture is a rapidly expanding sector that contributes significantly to the global food supply, with Asia accounting for 90% of production and India being the second largest aquaculture fish producer. Probiotics are used in aquaculture techniques because of the need for aquatic organism development, higher disease resistance, and feed efficiency. Several potential probiotics have been shown to produce antimicrobial substances that inhibit the growth of harmful microbes and preserve intestinal microecological equilibrium by allowing them to stick to stomach surfaces, thus impairing pathogenic growth. Aquaculture has benefited various industries, pharmaceuticals, and global food security in recent decades. Nevertheless, the stress conditions that aquatic creatures experience in aquaculture cause fish to become less resilient to illness and weaken their immune systems. Therefore, impacts local people's socioeconomic conditions and economic progress in many nations. Several approaches, including conventional practices, artificial chemicals, and antibiotics, have been used to control disease in the aquaculture sector. Hence, alternative techniques are far more important to keep the microbial ecosystem in aquaculture systems healthy. This review presents the current understanding of probiotic use in aquaculture as a healthy alternative for fish and biological control agents in aquaculture and to find out its future direction for research. [ABSTRACT FROM AUTHOR]

Flavobacterium psychrophilum is currently one of the most important pathogens in aquaculture worldwide, causing high losses to farmed salmonids particularly during early growth stages with significant economic impact. Despite previous attempts, no effective vaccine has been developed, and protection against introduction into farms is difficult due to the ubiquitous occurrence of the pathogen. A better understanding of the mechanism of disease development is essential for targeted therapeutic and preventive measures in farms. Unfortunately, the pathogenesis of diseases caused by F. psychrophilum has not been elucidated yet. Previously, several putative virulence factors have been identified. Some appear to be essential for disease development, while others are probably dispensable. The importance of some factors has not yet been explored. This review focuses on the supposed virulence factors of F. psychrophilum and the current knowledge about their importance in the pathogenesis of the disease. [ABSTRACT FROM AUTHOR]

Fisheries and aquaculture are notably known as the most important sources of protein that can provide food for billions of people worldwide. The aquatic farming production keeps expanding gradually in recent years professing that fisheries and aquaculture has become the fastest growing food-producing market. This sector continues to attract great interest from everyone due to its promising contribution in global food security, economic and social development. However, growing high density of marine culture to maximize the production has caused the aquatic animals to be vulnerable to diseases. Various infectious fish diseases have led to high fish mortality that later poses a significant threat to companies' long-term viability and countries' socio-economic development. Therefore, this review discusses fish diseases and the overview of fish vaccines as one of the approaches to ensure a sustainable future for aquaculture. [ABSTRACT FROM AUTHOR]

In the aquaculture system of ornamental fish, the interaction between bacterial microbiota and ciliate protozoa can prevent or promote disease outbreaks, and different physicochemical conditions will affect the relationships between them. We investigated the interaction between bacterial microbiota and the parasite Tetrahymena pyriformis when infecting Poecilia reticulata (guppy) under different physicochemical conditions. The abundance of T. pyriformis in water, the relative abundance of bacterial species, and histopathological observation were studied or monitored using environmental DNA (eDNA) extraction technology, the qPCR method, and 16s rRNA sequencing, respectively. The morphological identification and phylogenetic analysis of T. pyriformis were carried out. The infected guppy tissue was also stained by the hematoxylin and eosin methods. The results showed: (1) the bacterial communities of water samples were mainly composed of species assigned to Proteobacteria and Bacteroidetes, and Tabrizicola and Puniceicoccaceae were positively correlated with fish mortality, T. pyriformis abundance, and temperature. (2) Arcicella and Methyloversatilis universalis with different correlations between ciliates appeared in different treatment groups, the result of which proved that environmental factors affected the interaction between bacteria and T. pyriformis. (3) Lower temperatures and a higher pH were more beneficial for preventing disease outbreaks.

Peacock bass (syn.: tucunaré, Cichla ocellaris) and the pearl cichlids (syn.: acará, Geophagus brasiliensis) are South American cichlids that are highly valued in both the ornamental and sport fish industries. Since 2017, a number of outbreaks of infectious spleen and kidney necrosis virus (ISKNV) have been reported on Brazilian food and ornamental fish farms. In this study, we detected ISKNV in farmed peacock bass and pearl cichlid by PCR and sequence analysis of the partial major capsid protein (MCP) gene. Moribund peacock bass (n=10) and pearl cichlids (2) from a farm experiencing elevated mortality among juveniles and adults of these species, were submitted for bacteriological and molecular diagnostics. Spleen, liver, brain, and kidney tissues were cultured on 5% sheep blood agar and cystine heart agar with 1% glucose and bovine haemoglobin. No bacteria were isolated from the 12 fish. Additionally, DNA extracts from the liver and spleen of all animals were tested for ISKNV using two conventional polymerase chain reaction (cPCR) assays and two nested PCR (nPCR) assays. ISKNV DNA was amplified in all 12 fish DNA extracts tested, in two or more of the PCR assays. Selected ISKNV amplicons were confirmed by Sanger sequencing. The nucleotide sequences derived from these animals were identical to ISKNV strains previously detected in food (e.g., tilapia and carp) and ornamental species, including strains previously detected in fish from Brazil. To the authors’ knowledge, this is the first report of ISKNV in these native Brazilian cichlids.

Aquaculture, a rapidly expanding global food sector faces challenges like pathogenic infections, water quality management and sustainability. Silver nanoparticles (AgNPs) have emerged as promising tools in aquaculture due to their antimicrobial, antiviral and antifungal properties. AgNPs offer alternatives to traditional antimicrobial agents. Their small size and unique physicochemical properties enhance antimicrobial activity, effectively inhibiting pathogen growth and reducing disease incidence in aquatic organisms. Additionally, AgNPs can improve water quality by catalyzing the removal of pollutants, heavy metals and nutrients, reducing environmental impacts. Despite their potential benefits, several challenges and knowledge gaps exist in the utilization of AgNPs in aquaculture. Addressing challenges related to regulation, sustainability and environmental impact will be crucial for realizing their full potential in the industry. Therefore, the present review aims to provide insight into the role of AgNPs, its challenges in aquaculture and also highlights key areas for future research.

Aquaculture is playing an increasingly important role in global food security, especially for low-income and food-deficit countries. The majority of aquaculture production occurs in freshwater earthen ponds and tilapia has quickly become one of the most widely adopted culture species in these systems. Tilapia are now farmed in over 140 countries facilitated by their ease of production, adaptability to a wide range of environmental conditions, fast growth, and high nutritional value. Typically, tilapia have been considered a hardy, disease resilient species; however, the disease is increasing with subsequent threats to the industry as their production is intensified. In this review, we discuss tilapia production, with a focus on Bangladesh as one of the top producing countries, and highlight the problems associated with disease and treatment approaches for them, including the misuse of antimicrobials. We address a key missing component in understanding health and disease processes for sustainable production in aquaculture, specifically the role played by the microbiome. Here we examine the importance of the microbiome in supporting health, focused on the symbiotic microbial community of the fish skin mucosal surface, the abiotic and biotic factors that influence the microbiome, and the shifts that are associated with diseased states. We also identify conserved taxa of skin microbiomes that may be used as indicators of health status for tilapia offering new opportunities to mitigate and manage the disease and optimize environmental growing conditions and farming practices. [ABSTRACT FROM AUTHOR]

Lates calcarifer herpesvirus (LCHV) causes an emerging serious disease in aquaculture. Sudden drops in feed rates and mortality spikes exceeding 40%–50% often accompany LCHV infections in juvenile L. calcarifer, soon after transfer into sea cages. Affected fish have patchy white skin and fins, corneal opacity and frequently hang in surface water column like 'ghost' or 'zombie' fish. Fish have pale gills, fluid‐filled intestines with yellowish casts, lipid depleted liver, enlarged spleen and kidney and reddened brain. Epithelial hyperplasia, apoptosis, marginated nuclear chromatin, amphophilic intranuclear inclusion bodies and the occasional multinucleated cells are observed in gills, skin, intestines, liver and kidney. These are often accompanied by lymphocytic‐monocytic infiltration and extensive necrosis in gills, skin, kidney and intestines. Martius scarlet blue stains indicate presence of fibrin in vasculature in brain, gills, intestines, kidney and liver, or disseminated intravascular coagulation (DIC). DIC has been reported in human herpesviral infections. Multifocal lifting of intestinal epithelium with proteinaceous exudate and necrosis of several adjacent villi often progress to involve entire gut sections. Atrophied livers with accentuated lobules may progress to marked loss of hepatic acini. Multifocal dilated attenuated renal tubules are often accompanied by casts and marked protein loosing renopathy. This study on LCHV demonstrates that it can cause significant pathology and mortality. [ABSTRACT FROM AUTHOR]

Aquaculture fish diseases pose a serious threat to the security of food supplies. Fish species vary widely, and because they resemble one another so much, it is challenging to distinguish between them based solely on appearance. To stop the spread of disease, it is important to identify sick fish as soon as possible. Due to a lack of necessary infrastructure, it is still difficult to identify infected fish in aquaculture at an early stage. It is essential to promptly identify sick fish to stop the spread of disease. The purpose of this work is to suggest a machine learning technique based on the DCNN method for identifying and categorizing fish diseases. To solve problems involving global optimization, this paper suggests a brand-new hybrid algorithm called the Whale Optimization Algorithm with Genetic Algorithm (WOA-GA) and Ant Colony Optimization. In this work, for classification, the hybrid Random Forest algorithm is used. To facilitate the increased quality, distinctions between both the proposed WOA-GA-based DCNN architecture and the presently used methods for machine learning have been made. The effectiveness of the proposed detection technique is done with MATLAB. Performance metrics like sensitivity, specificity, accuracy, precision, recall, F-measure, NPV, FPR, FNR, and MCC are compared to the performance of the proposed technique. [ABSTRACT FROM AUTHOR]

The increasing global population has escalated the demand for fish products. This calls for a stable supply which can only be met through improved aquaculture practices. The automatic recognition of fish diseases from diseased underwater images is one of such practices that aims to control disease, improve fish production and optimize profits. However, due to lack of public fish disease dataset, there has been limited research towards fish disease recognition. Moreover, due to low quality of underwater images and complex underwater environments, traditional hand-designed feature extraction methods or convolutional neural networks (CNNs)-based classifiers cannot adequately recognize fish diseases in real underwater scenes. Therefore, this paper proposes a novel hybrid approach based on multilayer fusion, attention mechanism and online sequential extreme learning machine (OSELM) to recognize fish diseases in aquaculture. We further compare the classification performance of the proposed model with baseline, attention-based, ConvNeXt and Swin transformer models. Feature extraction is enhanced by integrating same level features and focusing on salient features for fish disease recognition. The characteristic information of fish disease is refined by using strongly discriminative features of the infected fish regions and weakening regions of low interest using convolutional block attention module (CBAM). The module is added to the multilayer fusion network to sequentially infer attention maps along the channel and spatial dimensions for every intermediate feature map. Fish disease recognition is then done using OSELM for faster learning and improved classification performance. The models are trained, validated and tested on a custom dataset with image samples collected from various internet sources. The proposed method achieves 94.28% of accuracy, precision of 92.67%, recall of 92.17% and 92.42% of F1- score on dataset with background elimination. The proposed method can be used for fish disease identification in complex underwater environments in aquaculture.

Simple Summary: In recent decades, trade of ornamental fish has significantly increased. A rise in demand was observed, especially from top importing countries that contributed majorly to the growth of the market. The destructive fishing methods caused a severe impairment of natural and environmental resources. Thus, there is a need to improve ornamental fish aquaculture, increasing the number of cultured species and limiting wild fish handling and transport stress losses. In this light, the use of microbial feed additives such as probiotics, prebiotics, and synbiotics, could help in improving the immune system and growth as well as increasing reproductive performance in captivity-bred species. Ornamental fish trade represents an important economic sector with an export turnover that reached approximately 5 billion US dollars in 2018. Despite its high economic importance, this sector does not receive much attention. Ornamental fish husbandry still faces many challenges and losses caused by transport stress and handling and outbreak of diseases are still to be improved. This review will provide insights on ornamental fish diseases along with the measures used to avoid or limit their onset. Moreover, this review will discuss the role of different natural and sustainable microbial feed additives, particularly probiotics, prebiotics, and synbiotics on the health, reduction in transport stress, growth, and reproduction of farmed ornamental fish. Most importantly, this review aims to fill the informational gaps existing in advanced and sustainable practices in the ornamental fish production. [ABSTRACT FROM AUTHOR]

A primary problem affecting the sustainable development of aquaculture is fish skin diseases. In order to prevent the outbreak of fish diseases and to provide prompt treatment to avoid mass mortality of fish, it is essential to detect and identify skin diseases immediately. Based on the YOLOv4 model, coupled with lightweight depthwise separable convolution and optimized feature extraction network and activation function, the detection and identification model of fish skin disease is constructed in this study. The developed model is tested for the diseases hemorrhagic septicemia, saprolegniasis, benedeniasis, and scuticociliatosis, and applied to monitor the health condition of fish skin in deep-sea cage culture. Results show that the MobileNet3-GELU-YOLOv4 model proposed in this study has an improved learning ability, and the number of model parameters is reduced. Compared to the original YOLOv4 model, its mAP and detection speed increased by 12.39% and 19.31 FPS, respectively. The advantages of the model are its intra-species classification capability, lightweight deployment, detection accuracy, and speed, making the model more applicable to the real-time monitoring of fish skin health in a deep-sea aquaculture environment. [ABSTRACT FROM AUTHOR]

Aeromonas species are associated with diseases on fish farms leading to mortality and economic losses. In order to determine the prevalence and diversity of Aeromonas species from water and Clarias gariepinus cultured in the different holding facilities; five hundred and seventy six Clarias gariepinus fish and one hundred and eight water samples were randomly sampled from fish farms in Kwara State. The samples were clinically and bacteriologically examined and confirmed using Oxiod rapid microbat identification test kits for Gram-negative bacteria, Microbact 24E (MB24E). The overall prevalence of Aeromonas species from water from the different cultured facilities revealed water sampled from earthen ponds had the highest prevalence of 66.67 % followed by concrete tanks with a prevalence of 41.66 % and the least prevalence of 30.56 % was recorded for water in plastic tanks. A similar pattern was recorded in Clarias gariepinus from the different holding facilities showing that earthen ponds had the highest prevalence of 40.10 % when compared with concrete tanks 28.65%, and to plastic tanks 20.83 %. Four varying diversities of Aeromonas species comprising of Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii biovar sobria, and Aeromonas veronii biovar veronii were isolated from both water and fish from the different holding facilities. From this study, cultured Clarias gariepinus were susceptible to Aeromonas species irrespective of the culture facilities. Therefore, Therefore, there is need for proper management practices and adherence to biosecurity measures to prevent the outbreak and spread of diseases on the farms. [ABSTRACT FROM AUTHOR]

Highlight Research • Feeding of maggot flour formulations to koi carp infected with tarda • Active compounds contained in maggot • Clinical symptoms of koi carp infected with tarda • Damage to the muscle and gill tissue of koi carp infected with E. tarda Abstract The problem that fishes farmers often face is disease. Maggot contains a high protein which ranges from 41-42%. Besides that, maggot also has a good effect on increasing the body resistance of fish. While the maggot provision fulfills nutritional need, it's also expected to boost immunity against bacterial disease. One of which is Edwardsiella tarda, known to infect koi carp (Cyprinus carpio). Feeding of maggot flour at different doses, namely A (25%), B (50%), C (75%), and D (100%) was carried out to determine its effect on the histopathology of the muscles and gills of C. carpio infected with E. tarda. Water quality during the study obtained an average value, namely the temperature ranging from 26-27.5℃, pH 6.5-8.1, and DO 5.2-8 mg/L. Fish infected with E. tarda showed several clinical symptoms, including rapid operculum movement, irregular and slow swimming, and bleeding on the skin. The results of the histopathological analysis showed that in muscle and gill tissue, treatment C (75%) showed the lowest damage value among other treatments with an average score of necrosis 0.93, hyaline degeneration 1.33, and Edema 1.27. Average score of gill tissue damage was 0.9 fusion, 1.3 congestion, 0.9 hyperplasia. Based on this, the provision of maggot flour can be used to prevent infection of E. tarda against C. carpio.

Organisms release their nucleic acid in the environment, including the DNA and RNA, which can be used to detect their presence. eDNA/eRNA techniques are being used in different sectors to identify organisms from soil, water, air, and ice. The advancement in technology led to easier detection of different organisms without impacting the environment or the organism itself. These methods are being employed in different areas, including surveillance, history, and conservation. eDNA and eRNA methods are being extensively used in aquaculture and fisheries settings to understand the presence of different fish species and pathogens in water. However, there are some challenges associated with the reliability of results because of the degradation of nucleic acid by several factors. In aquaculture, there are several diseases and parasites detected with these methods. In this review, we discuss different aquaculture diseases and parasites detected with eDNA/eRNA approach and the fate of these nucleic acids when subjected to different water quality and environmental parameters. This review intends to help the researcher with the potential of eDNA/eRNA-based detection of pathogens in aquaculture; this will be useful to predict a potential outbreak before it occurs. Along with that, this paper intends to help people understand several factors that degrade and can hamper the detection of these nucleic acids. [ABSTRACT FROM AUTHOR]

Objective: The research was conducted to investigate the disease prevalence and use of veterinary antibiotics in land-based aquaculture for fish health management in South Chattogram, Bangladesh. Materials and Methods: Data were collected using participatory rural appraisal tools such as market surveys, personal contact, and questionnaire interviews with 80 fish farmers, 10 technical officers from different pharmaceutical companies, and 10 chemical sellers from the South Chattogram Upazilas of Chakoria, Anwara, Lohagara, Banshkhali, and Coxs Bazar Sadar. Results: A total of 37 brands belonging to 10 distinct antibiotic groups were identified. Erythromycin, sulfadyazine, trimethoprim (97.5%), and oxytetracycline (95%) were found to be the most commonly utilized antibiotics. Tilapia infection (91.25%) and Edwardsiellosis in pangas (80%) were the most encountered diseases. Mixed cultures of tilapia, carp, and pangas were the most common cultural practices. A number of limitations were found, including the farmers lack of knowledge on how to appropriately handle antibiotics that were incorporated into the research. Conclusion: The findings show that disease has become a common and rising concern in aquaculture, and without a formal diagnosis, farmers are using various antibiotics. The subsequent concern over antibiotic residues impact on the environment, animal, and human health demands extensive investigation to detect possible hazards in other parts of Bangladesh, specifically in south Chattogram. [Vet. Res. Notes 2022; 2(2.000): 15-21]

Diseases are a significant impediment to aquaculture's sustainable and healthy growth. The aquaculture industry is suffering significant financial losses as a result of the worsening water quality and increasing frequency of aquatic disease outbreaks caused by the expansion of aquaculture. Drug control, immunoprophylaxis, ecologically integrated control, etc. are the principal control strategies for fish infections. For a long time, the prevention and control of aquatic diseases have mainly relied on the use of various antibiotics and chemical drugs. However, long-term use of chemical inputs not only increases pathogenic bacteria resistance but also damages the fish and aquaculture environments, resulting in drug residues in aquatic products, severely impeding the development of the aquaculture industry. The development and use of aquatic vaccines are the safest and most effective ways to prevent aquatic animal diseases and preserve the health and sustainability of aquaculture. To give references for the development and implementation of aquatic vaccines, this study reviews the development history, types, inoculation techniques, mechanisms of action, development prospects, and challenges encountered with aquatic vaccines. [ABSTRACT FROM AUTHOR]

The problem that fishes farmers often face is disease. Maggot contains a high protein which ranges from 41-42%. Besides that, maggot also has a good effect on increasing the body resistance of fish. While the maggot provision fulfills nutritional need, it's also expected to boost immunity against bacterial disease. One of which is Edwardsiella tarda, known to infect koi carp (Cyprinus carpio). Feeding of maggot flour at different doses, namely A (25%), B (50%), C (75%), and D (100%) was carried out to determine its effect on the histopathology of the muscles and gills of C. carpio infected with E. tarda. Water quality during the study obtained an average value, namely the temperature ranging from 26-27.5°C, pH 6.5-8.1, and DO 5.2-8 mg/L. Fish infected with E. tarda showed several clinical symptoms, including rapid operculum movement, irregular and slow swimming, and bleeding on the skin. The results of the histopathological analysis showed that in muscle and gill tissue, treatment C (75%) showed the lowest damage value among other treatments with an average score of necrosis 0.93, hyaline degeneration 1.33, and Edema 1.27. Average score of gill tissue damage was 0.9 fusion, 1.3 congestion, 0.9 hyperplasia. Based on this, the provision of maggot flour can be used to prevent infection of E. tarda against C. carpio. [ABSTRACT FROM AUTHOR]

White grub metacercariae were found in the livers and kidneys of diseased specimens of an introduced channel catfish, Ictalurus punctatus (Rafinesque), in Vietnam. Based on morphological features and 28S rDNA sequence analysis, the isolated metacercariae were identified as Dollfustrema bagarii (Digenea: Bucephalidae) Moravec & Sey. Histopathological examination shows that encysted metacercariae can change the tissue structure of the infected organs and is often accompanied by haemorrhaging and the presence of eosinophilic granular cell infiltration. Degenerative changes were also observed. [ABSTRACT FROM AUTHOR]

Aquaculture is undoubtedly a flourishing industry that ensures food security for the increasing population. However, this industry is under severe threat from bacterial, viral, parasitic, and fungal infections besides environmental contamination. Hence, in the recent days, new technologies are surfacing to confront these challenges efficiently. Nanotechnology is one of the novel and pioneering skills with a wide continuum of applications ranging from aquatic pond sterilization, water treatment, nutrient delivery, diagnosis, drug delivery, aquatic disease control, etc. The present review is mainly focused on the application of nanomaterials in fish disease management to promote sustainable aquaculture. Specifically, the effects of gold, silver, copper oxide, zinc oxide, selenium, chitosan, platinum, etc., nanoparticles on pathogen identification and treatment of fish diseases are discussed in detail. In addition, the role of these nanoparticles in fish disease control is highlighted in this review. In contrast, this review also emphasizes the toxicity associated with nanoparticle-based fish disease management which will be helpful for fish culturists. • Fish is facing severe threat from different pathogens. • Nanoparticles are being used for diagnosis of diseases. • Various nanoparticles are in use for disease treatment. • Nanoparticles are being used to control the diseases. [ABSTRACT FROM AUTHOR]

A primary problem affecting the sustainable development of aquaculture is fish skin diseases. In order to prevent the outbreak of fish diseases and to provide prompt treatment to avoid mass mortality of fish, it is essential to detect and identify skin diseases immediately. Based on the YOLOv4 model, coupled with lightweight depthwise separable convolution and optimized feature extraction network and activation function, the detection and identification model of fish skin disease is constructed in this study. The developed model is tested for the diseases hemorrhagic septicemia, saprolegniasis, benedeniasis, and scuticociliatosis, and applied to monitor the health condition of fish skin in deep-sea cage culture. Results show that the MobileNet3-GELU-YOLOv4 model proposed in this study has an improved learning ability, and the number of model parameters is reduced. Compared to the original YOLOv4 model, its mAP and detection speed increased by 12.39% and 19.31 FPS, respectively. The advantages of the model are its intra-species classification capability, lightweight deployment, detection accuracy, and speed, making the model more applicable to the real-time monitoring of fish skin health in a deep-sea aquaculture environment.

Bacterial fish pathogens are one of the key challenges in the aquaculture industry, one of the fast-growing industries worldwide. These pathogens rely on arsenal of virulence factors such as toxins, adhesins, effectors and enzymes to promote colonization and infection. Translocation of virulence factors across the membrane to either the extracellular environment or directly into the host cells is performed by single or multiple dedicated secretion systems. These secretion systems are often key to the infection process. They can range from simple single-protein systems to complex injection needles made from dozens of subunits. Here, we review the different types of secretion systems in Gram-negative bacterial fish pathogens and describe their putative roles in pathogenicity. We find that the available information is fragmented and often descriptive, and hope that our overview will help researchers to more systematically learn from the similarities and differences between the virulence factors and secretion systems of the fish-pathogenic species described here. [ABSTRACT FROM AUTHOR]

'Big belly' disease is a chronic, granulomatous bacterial enteritis and peritonitis, first reported in 3‐ to 4‐week‐old Asian seabass or barramundi, Lates calcarifer Bloch fry. Affected fry are emaciated and have a swollen abdomen, and the condition is referred to as 'skinny pot‐belly' or 'big belly' disease. In this study, histopathological examinations of diseased fish from a batch of 2‐month‐old, 6‐ to 8‐cm L. calcarifer fingerlings, kept in seawater recirculating aquaculture systems, showed pathology resembling 'big belly' disease. Ethanol‐fixed tissues were tested positive using specific PCR primers based on 16S rRNA genes. In situ hybridization using dioxygenin‐labelled positive PCR products on formalin‐fixed paraffin‐embedded tissues showed positive reactions with intralesional, clusters of the large, 'big belly' coccobacilli. A phylogenetic tree constructed based on analyses of these 16S rRNA gene PCR products from five positive fish suggests that the 'big belly' bacterium is most likely a novel Vibrio species. [ABSTRACT FROM AUTHOR]

Abstract Background Infectious disease outbreaks form major setbacks to aquaculture production and to further development of this important sector. Cyprinid herpes virus-3 (CyHV-3) is a dsDNA virus widely hampering production of common carp (Cyprinus carpio), one of the most farmed fish species worldwide. Genetically disease resistant strains are highly sought after as a sustainable solution to this problem. To study the genetic basis and cellular pathways underlying disease resistance, RNA-Seq was used to characterize transcriptional responses of susceptible and resistant fish at day 4 after CyHV-3 infection. Results In susceptible fish, over four times more differentially expressed genes were up-regulated between day 0 and 4 compared to resistant fish. Susceptible and resistant fish responded distinctively to infection as only 55 (9%) of the up-regulated genes were shared by these two fish types. Susceptible fish elicited a typical anti-viral response, involving interferon and interferon responsive genes, earlier than resistant fish did. Furthermore, chemokine profiles indicated that the two fish types elicited different cellular immunity responses. A comparative phylogenetic approach assisted in chemokine copies annotation pointing to different orthologous copies common to bony-fishes and even carp-specific paralogs that were differentially regulated and contributed to the different response of these two fish types. Susceptible fish up-regulated more ccl19 chemokines, which attract T-cells and macrophages, the anti-viral role of which is established, whereas resistant fish up-regulated more cxcl8/il8 chemokines, which attract neutrophils, the antiviral role of which is unfamiliar. Conclusions Taken together, by pointing out transcriptional differences between susceptible and resistant fish in response to CyHV-3 infection, this study unraveled possible genes and pathways that take part in disease resistance mechanisms in fish and thus, enhances our understanding of fish immunogenetics and supports the development of sustainable and safe aquaculture.

Bacterial fish pathogens are one of the key challenges in the aquaculture industry, one of the fast-growing industries worldwide. These pathogens rely on arsenal of virulence factors such as toxins, adhesins, effectors and enzymes to promote colonization and infection. Translocation of virulence factors across the membrane to either the extracellular environment or directly into the host cells is performed by single or multiple dedicated secretion systems. These secretion systems are often key to the infection process. They can range from simple single-protein systems to complex injection needles made from dozens of subunits. Here, we review the different types of secretion systems in Gram-negative bacterial fish pathogens and describe their putative roles in pathogenicity. We find that the available information is fragmented and often descriptive, and hope that our overview will help researchers to more systematically learn from the similarities and differences between the virulence factors and secretion systems of the fish-pathogenic species described here.

In recent decades, aquaculture has played a significant role in fulfilling the vast demand for animal protein requirements and consequently in food security. However, environmental contamination and disease prevalence are considered essential challenges for the sector. In this regard, new approaches have been paved in technology to deal effectively with such challenges. Among these, nanotechnology—as a novel and innovative tool—has a broad spectrum of uses and a tremendous potential in aquaculture and seafood preservation. It can provide new technologies for management of drugs as liberation of vaccines and therefore hold the assurance for civilized protection of farmed fish against disease-causing pathogens. This article presents a review of nanotechnology and its applications in aquaculture. Additionally, it gives a brief idea about the fish disease and classical ways of controlling pathogens. On the other hand, this review sheds the light on nanotechnology as a potential novel tool which may possibly enhance the management and the control of disease prevalence. Therefore, the importance of this technology to promote sustainable aquaculture has also been highlighted. Focusing on the role of selenium nanoparticles as an efficient element is discussed also in this article. [ABSTRACT FROM AUTHOR]

Kematian ikan akibat serangan parasit Argulus dikarenakan ikan mengalami emasiasi sehingga dapat menurunkan sistem kekebalan tubuh ikan, selain itu munculnya luka pada kulit ikan akan dimanfaatkan sebagai port of entry bagi agen infeksi sekunder seperti jamur, bakteri dan virus. Pengendalian penyakit argulosis dengan bahan kimia yang tidak tepat dosis dapat mencemari lingkungan, sehingga perlu dicari alternatif bahan kimia yang aman terhadap lingkungan, yaitu abate. Tujuan dari penelitian ini yaitu untuk mengetahui efektivitas perendaman abate untuk menurunkan derajat infestasi dan merusak organ parasit Argulus yang menginfestasi ikan mas (Cyprinus carpio). Perlakuan yang diberikan terdiri dari lima perlakuan dengan empat kali ulangan yaitu pemberian abate dengan konsentrasi 0 ppm (kontrol), 25 ppm, 50 ppm, 75 ppm, dan 100 ppm yang direndam selama 30 menit. Parameter yang diamati pada penelitian ini yaitu derajat infestasi Argulus yang menempel pada ikan mas, kerusakan organ Argulus dan nilai kualitas air pada awal dan akhir perendaman sebagai parameter pendukung. Data derajat infestasi Argulus pada ikan mas dianalisis secara statistik menggunakan ANOVA 5% yang dilanjutkan dengan uji DMRT 5% sedangkan kerusakan organ Argulus dianalisis secara deskriptif dan disajikan dalam bentuk gambar dan tabel serta dihubungkan dengan parameter pendukung. Hasil penelitian menujukkan bahwa perendaman abate tidak efektif untuk menurunkan derajat infestasi menginfestasi ikan mas (C. carpio), akan tetapi dapat menimbulkan kerusakan organ Argulus pada perlakuan 100 ppm. Kerusakan organ Argulus yang ditimbulkan yaitu rontoknya kaki ke-3 dan 4, abdomen yang menyatu serta produksi telur prematur. Perlu dilakukan penelitian lanjutan dengan meningkatkan dosis abate (lebih dari 100 ppm) serta waktu inkubasi yang lebih lama (lebih dari 30 menit). Selain itu perlu diamati perubahan fisiologis ikan selama dilakukan perendaman dalam abate.

Salmon gill poxvirus (SGPV) can cause serious gill disease in Atlantic salmon (Salmo salar L.) and represents a significant problem to aquaculture industries in Northern Europe. Here, a single-tube multi-locus variable-number tandem-repeat (VNTR) analysis (MLVA) genotyping assay, targeting eight VNTR loci, was developed for studying the epizootiology of SGPV. Through MLVA typing of SGPV positive samples from 180 farmed and wild Atlantic salmon in Northern Europe, the first molecular population study of this virus was undertaken. Comparison of resulting MLVA profiles by cluster analysis revealed considerable micro-diversity, while only a limited degree of specific clustering by country of origin could be observed, and no clustering relating to the severity of disease outbreaks. Phylogenetic analysis, based on genomic data from six SGPV specimens (three Norwegian, one Scottish, one Faroese and one Canadian), complemented and corroborated MLVA by pointing to a marked transatlantic divide in the species, with one main, relatively conserved, SGPV lineage as predominant in Europe. Within certain fjord systems and individual freshwater salmon smolt farms in Norway, however, discrete MLVA clustering patterns that prevailed over time were observed, likely reflecting local predominance of specific SGPV sub-lineages. MLVA typing was also used to refute two suspected instances of vertical SGPV transmission from salmon broodstock to offspring, and to confirm a failed disinfection attempt in one farm. These novel insights into the previously undocumented population structure of SGPV provide important clues, e.g., regarding the mechanisms underlying spread and recurrence of the virus amongst wild and farmed salmon populations, but so far no indications of more or less virulent SGPV sub-lineages have been found. The MLVA scheme represents a highly sensitive genotyping tool particularly well suited for illuminating SGPV infection routes, and adds to the relatively low number of MLVA protocols that have so far been published for viral species. Typing is reasonably inexpensive, with a moderate technological requirement, and may be completed within a single working day. Resulting MLVA profiles can be readily shared and compared across laboratories, facilitating rapid placement of samples in an international ezpizootiological context. [ABSTRACT FROM AUTHOR]

Dawestrema cycloancistrium is the main ectoparasite causing mortality in fingerlings of pirarucu (Arapaima gigas) in Amazonian aquaculture. Very little is known about the D. cycloancistrium reproductive index and appropriate methods of collecting eggs for investigation. This study aimed to determine the oviposition rate of D. cycloancistrium. To achieve this aim, two egg quantification methods were tested: the estimative method (ME) and the total counting method (MT). Compared with the MT, the ME overestimated the number of eggs counted, which were 2943.5 ± 2840.6 and 1041.5 ± 533 eggs, and the oviposition rate, which was 80.1 ± 58.7 and 31.4 ± 16.4 eggs/parasite/day, for ME and MT, respectively. These results show that for studies quantifying D. cycloancistrium eggs, the total eggs in the sample must be counted, as the estimates made using subsamples are not representative. Using the MT, the oviposition rate for D. cycloancistrium was determined to be 31.4 ± 16.4 eggs per adult parasite per day. The present study demonstrates the egg production capacity of a monogenean species parasite of A. gigas , providing basic biological data for D. cycloancistrium. [ABSTRACT FROM AUTHOR]

Background: Infectious disease outbreaks form major setbacks to aquaculture production and to further development of this important sector. Cyprinid herpes virus-3 (CyHV-3) is a dsDNA virus widely hampering production of common carp (Cyprinus carpio), one of the most farmed fish species worldwide. Genetically disease resistant strains are highly sought after as a sustainable solution to this problem. To study the genetic basis and cellular pathways underlying disease resistance, RNA-Seq was used to characterize transcriptional responses of susceptible and resistant fish at day 4 after CyHV-3 infection. Results: In susceptible fish, over four times more differentially expressed genes were up-regulated between day 0 and 4 compared to resistant fish. Susceptible and resistant fish responded distinctively to infection as only 55 (9%) of the up-regulated genes were shared by these two fish types. Susceptible fish elicited a typical anti-viral response, involving interferon and interferon responsive genes, earlier than resistant fish did. Furthermore, chemokine profiles indicated that the two fish types elicited different cellular immunity responses. A comparative phylogenetic approach assisted in chemokine copies annotation pointing to different orthologous copies common to bony-fishes and even carp-specific paralogs that were differentially regulated and contributed to the different response of these two fish types. Susceptible fish up-regulated more ccl19 chemokines, which attract T-cells and macrophages, the anti-viral role of which is established, whereas resistant fish up-regulated more cxcl8/il8 chemokines, which attract neutrophils, the antiviral role of which is unfamiliar. Conclusions: Taken together, by pointing out transcriptional differences between susceptible and resistant fish in response to CyHV-3 infection, this study unraveled possible genes and pathways that take part in disease resistance mechanisms in fish and thus, enhances our understanding of fish immunogenetics and supports the development of sustainable and safe aquaculture. [ABSTRACT FROM AUTHOR]

Catfish production is a major aquaculture industry in the United States and is the largest sector of food fish production. As producers aim to optimize production yields, diseases caused by bacterial pathogens are responsible for high pond mortality rates and economic losses. The major bacterial pathogens responsible are Edwardsiella ictaluri, Aeromonas spp., and Flavobacterium columnare. Given the outdoor pond culture environments and ubiquitous nature of these aquatic pathogens, there have been many reports of co-infective bacterial infections within this aquaculture sector. Co-infections may be responsible for altering disease infection mechanics, increasing mortality rates, and creating difficulties for disease management plans. Furthermore, proper diagnoses of primary and secondary pathogens are essential in ensuring the correct treatment approaches for antimicrobials and chemical applications. A thorough understanding of the interactions and infectivity dynamics for these warm water bacterial pathogens will allow for the adoption of new prevention and control methods, particularly in vaccine development. This review aims to provide an overview of co-infective pathogens in catfish culture and present diagnostic case data from Mississippi and Alabama to define prevalence for these multiple-species infections better.

Aquaculture is an important industry globally as it remains one of the significant alternatives of animal protein source supplies for humankind. Yet, the progression of this industry is being dampened by the increasing rate of fish mortality, mainly the outbreak of infectious diseases. Consequently, the regress in aquaculture ultimately results in the economy of multiple countries being affected due to the decline of product yields and marketability. By 2025, aquaculture is expected to contribute approximately 57% of fish consumption worldwide. Without a strategic approach to curb infectious diseases, the increasing demands of the aquaculture industry may not be sustainable and hence contributing to the over-fishing of wild fish. Recently, a new holistic approach that utilizes multi-omics platforms including transcriptomics, proteomics, and metabolomics is unraveling the intricate molecular mechanisms of host-pathogen interaction. This approach aims to provide a better understanding of how to improve the resistance of host species. However, no comprehensive review has been published on multi-omics strategies in deciphering fish disease etiology and molecular regulation. Most publications have only covered particular omics and no constructive reviews on various omics findings across fish species, particularly on their immune systems, have been described elsewhere. Our previous publication reviewed the integration of omics application for understanding the mechanism of fish immune response due to microbial infection. Hence, this review provides a thorough compilation of current advancements in omics strategies for fish disease management in the aquaculture industry. The discovery of biomarkers in various fish diseases and their potential advancement to complement the recent progress in combatting fish disease is also discussed in this review.

The article offers information on the prevalence and genotypes of infectious salmon anaemia virus in returning wild Atlantic salmon in northern Norway. Topics discussed include information on the Infectious salmon anaemia as a serious viral disease of Atlantic salmon; discussions on the examinations of the outbreak areas by which salmon exposed to the virus; and the information on the examination of the phylogenetic relationship to other infectious salmon anaemia highly polymorphic regions.

Abstract In this study, we investigated the immune responses against Mycobacterium gordonae in ginbuna crucian carp. Cumulative mortality of ginbuna injected with 2.0 × 107 CFU of M. gordonae was 50% at 170 days post-infection. CD4-1, CD8α, T-bet and IFNγ2 gene expression levels were significantly upregulated in ginbuna injected with 1.9 × 108 CFU of M. gordonae at 21 and 28 days post-infection. The CD4-2 level did not change during the experiment. Granulomatous responses consisted of central macrophage accumulation and surrounding lymphocytes, and Ziehl-Neelsen-positive bacteria were observed in the trunk kidney of the challenged fish. Immunohistochemistry using anti-ginbuna IFNγs and anti-ginbuna CD4-1 polyclonal antibody revealed that the marginal lymphocytes were positive for CD4-1, and the IFNγ-producing cells surrounded the mycobacterial cell-laden phagocytes. These results suggest that CD4-1+ cells and IFNγ2 play important roles in the granulomatous inflammation against Mycobacterial infections in teleosts. Highlights • Granulomas were observed in the trunk kidney of M. gordonae challenged fish. • CD4-1, CD8α and IFNγ2 levels were upregulated in the trunk kidney of challenged fish. • The marginal lymphocytes in the granuloma were positive for CD4-1 molecule. • IFNγ+ cells surrounded the mycobacterial cell-laden phagocytes in the granuloma. • CD4-1+ cells and IFNγ+ cells play important roles in the granulomatous inflammation. [ABSTRACT FROM AUTHOR]

Understanding ecological and epidemiological factors driving pathogen evolution in contemporary time scales is a major challenge in modern health management. Pathogens that replicate outside the hosts are subject to selection imposed by ambient environmental conditions. Increased nutrient levels could increase pathogen virulence by pre-adapting for efficient use of resources upon contact to a nutrient rich host or by favouring transmission of fast-growing virulent strains. We measured changes in virulence and competition in Flavobacterium columnare, a bacterial pathogen of freshwater fish, under high and low nutrient levels. To test competition between strains in genotype mixtures, we developed a quantitative real-time PCR assay. We found that a virulent strain maintained its virulence and outcompeted less virulent strains independent of the nutrient level and resource renewal rate while a less virulent strain further lost virulence in chemostats under low nutrient level and over long-term serial culture under high nutrient level. Our results suggest that increased outside-host nutrient levels might maintain virulence in less virulent strains and increase their contribution to epidemics in aquaculture. The results highlight a need to further explore the role of resource in the outside-host environment in maintaining strain diversity and driving evolution of virulence among environmentally growing pathogens. [ABSTRACT FROM AUTHOR]

Ciliates of the family Trichodinidae are protozoan parasites of importance for fish farming in South America, given that at high infestation levels, they cause significant mortality among farmed fish. Although data on economic losses due to parasitosis are not available for South America, mortality outbreaks correlated to trichodinids are very common in the tilapia production chain, especially in Brazil, the largest aquaculture chain in the country. In Brazil in the past, trichodinids were considered only as Trichodina sp. Today, they have been better studied and identified taxonomically in wild and farmed fish. However, in other countries in South America, trichodinids continue to be described only as Trichodina sp. This review presents the history of occurrences of trichodinids in fish of interest in South America, highlighting 15 new species that have been described in three genera in Brazil, along with information on parasite-host-environment relationships, diagnostic methods and treatments. The occurrence of parasitic ciliates must be correlated with farming conditions such as stress factors, water quality, seasonality, age and host immunity to elucidate the critical points of each production system. Furthermore, for tropical fish, studies on treatment against trichodinid species are needed to provide support for approval of antiparasitic medications for use in fish farming. However, it is recommended that the production sector use intensive production systems that are more sustainable, with biosafety protocols, to increase production and productivity. [ABSTRACT FROM AUTHOR]

With the expanding of marine and freshwater aquaculture, the outbreaks of aquatic animal diseases have increasingly become the major threats to the healthy development of aquaculture industries. Notably, viral infections lead to massive fish deaths and result in great economic loss every year across the world. Hence, it is meaningful to clarify the biodiversity, geographical distribution and host specificity of fish-associated viruses. In this study, viral sequences detected in fish samples were manually collected from public resources, along with the related metadata, such as sampling time, location, specimen type and fish species. Moreover, the information regarding the host fish, including aliases, diet type and geographic distribution were also integrated into a database (FVD). To date, FVD covers the information of 4860 fish-associated viruses belonging to 15 viral families, which were detected from 306 fish species in 57 countries. Meanwhile, sequence alignment, live data statistics and download function are available. Through the user-friendly interface, FVD provides a practical platform that would not only benefit virologists who want to disclose the spread of fish-associated viruses, but also zoologists who focus on the health of domestic and wild animals. Furthermore, it may facilitate the surveillance and prevention of fish viral diseases. Database URL: http://bioinfo.ihb.ac.cn/fvd [ABSTRACT FROM AUTHOR]

Diseases are an important challenge in aquaculture. However, most of what is known about the effect of diseases comes from laboratory experiments. Using a farm-level data set containing sea lice infestation counts for all Norwegian salmon farms over an 84-month period, we empirically investigate the biological and economic impacts of observed levels of infective lice. Sea lice, a common ectoparasitic copepod of salmonids, have been shown to reduce fish growth and appetite and cause substantial costs to salmon farmers worldwide. Our results suggest that the percent of total biomass growth lost per production cycle due to average infestations varies from 3.62 to 16.55%, despite control, and depends on farm location. Using a discrete harvesting model, we simulate the economic impact on farm profits over typical cycles. An average infestation over a typical central region spring-release cycle generates damages of US$0.46 per kg of harvested biomass, equivalent to 9% of farm revenues. We estimate that lice parasitism produced US$436m in damages to the Norwegian industry in 2011. [ABSTRACT FROM AUTHOR]