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Fish diseases are among the major limiting factors to increase global aquaculture production. They lead to increased fish mortality, low breeding and growth rates, and low meat quality. The success of aquaculture is heavily dependent on the timely identification of disease. Therefore, we propose a fuzzy U-Net model to automatically identify fish disease from underwater images. U-Net is enhanced with multi-head channel and spatial attention and used to segment infected fish regions from fish disease images. Color pixel intensity features are then extracted from the localized regions, a form of guided feature extraction. Fuzzy C-means clustering is then used to find the cluster centroids and data distribution within the clusters, for the design of fuzzy membership functions. Moreover, the number of clusters are determined by silhouette score. Adaptive neuro-fuzzy inference system (ANFIS) is then trained, tested, and cross-validated for fish disease identification. The model parameters are optimized using particle swarm optimization (PSO) algorithm and compared with gradient-based methods. For image segmentation, the enhanced U-Net achieved a mean intersection over union (IoU) of 86.29%, mean pixel accuracy of 90.94%, mean precision of 93.58%, and mean recall value of 89.94% on 42 test images. Subsequently, ANFIS with PSO achieved overall superior performance on fish disease identification over gradient-based methods, with accuracy of 99.31%, precision of 99.00%, recall of 99.00%, and F1-score of 99.00%. The high-performance results of the optimized ANFIS confirm the robustness and efficacy of the proposed method to automatically identify fish diseases in aquaculture. [ABSTRACT FROM AUTHOR]

Prevalent etiological agents and treatment options are essential for diagnosing and managing fish diseases. Therefore, this study used standard microbiological procedures to enumerate and identify the total bacterial count in the water, skin, and gastrointestinal tract of 75 moribund cultured Clarias gariepinus from different culture facilities. Following that, the antibiotic susceptibility of the isolated bacteria to eight antibiotics was tested using the Kirby-Bauer disc diffusion method. Various clinical signs and pathological lesions were observed on the sampled moribund fish. Total bacterial count varied significantly (P < 0.05) regardless of the types of culture facilities. Bacteria species from eight different genera were present, comprising three Gram-positive bacteria, Bacillus subtilis, Streptococcus agalactiae, and Staphylococcus aureus, and five Gram-negative bacteria, Aeromonas hydrophila, Citrobacter freundii, Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica, in which Gram-negative bacteria (> 70%) were the most prevalent type of bacteria isolated. There was an association between the bacteria species isolated from the water and the different parts of the fish sampled regardless of the culture facilities. The antibiogram of the bacteria recovered revealed different sensitivity and resistance profiles. More than fifty percent of the Gram-negative bacteria were sensitive to ciprofloxacin, while the Gram-positive bacteria were susceptible to ciprofloxacin and gentamycin (> 40%). Amoxicillin, ampicillin oxytetracycline, and tetracycline resistance were high in the bacteria isolates. This study confirmed the presence of antibiotic-resistant pathogenic bacteria isolated with a multiple antimicrobial resistance (MAR) index of 0.63-0.75, indicating indiscriminate and irrational use of antibiotics. [ABSTRACT FROM AUTHOR]

Prevalent etiological agents and treatment options are essential for diagnosing and managing fish diseases. Therefore, in this study, enumeration and identification of the total bacterial count in water, skin, and gastrointestinal tract of 75 moribund cultured Clarias gariepinus from different culture facilities were investigated using standard microbiological procedures. Following that, the antibiotic susceptibility of the isolated bacteria to eight antibiotics was tested using the Kirby-Bauer disc diffusion method. Various clinical signs and pathological lesions were observed on the sampled moribund fish. Total bacterial count varied significantly (P < 0.05) regardless of the types of culture facilities. Bacteria species from eight different genera were present, comprising three Gram-positive bacteria; Bacillus subtilis, Streptococcus agalactiae, and Staphylococcus aureus; and five Gram-negative bacteria; Aeromonas hydrophila, Citrobacter freundii, Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica were identified in which Gram-negative bacteria (> 70 %) were the most prevalent type of bacteria isolated. There was an association between the bacteria species isolated from the water and the different parts of the fish sampled regardless of the culture facilities. The antibiogram of the bacteria recovered revealed different sensitivity and resistance profiles. More than fifty percent of the Gram-negative bacteria were sensitive to ciprofloxacin, while the Gram-positive bacteria were susceptible to ciprofloxacin and gentamycin (> 40 %). Amoxicillin, ampicillin oxytetracycline, and tetracycline resistance were high in the bacteria isolates. This study confirmed the presence of antibiotic-resistant pathogenic bacteria isolated with a multiple antimicrobial resistance (MAR) index of 0.63 - 0.75, indicating indiscriminate and irrational use of antibiotics.

This study investigated the effects of different dietary levels of Triphala fruit powder on the growth performance, histology, serum parameters, gene expression indicators, and survival of Nile tilapia (Oreochromis niloticus) fingerlings against Saprolegnia ferax infection. The fish were fed with either a control diet (without Triphala fruit powder addition) or three experimental diets including 1, 2, and 3% of TFP over a 60-day period. Two hundred and forty healthy fish (28.0 ± 0.2 g) were stocked in 12 tanks, 20 fish per tank. Dietary TFP supplementation significantly improved growth performance and feed efficiency to the un-treated group (P < 0.05). All Triphala fruit powder dietary groups had a significant higher amylase activity and lower levels of ALT, AST, and cholesterol than the control group (P < 0.05). The Triphala fruit powder treatment (3%) resulted in a significant increase in packed cell volume, red blood cell count, haemoglobin, and monocyte values compared to other groups (P < 0.05). The study reported significant (P < 0.05) improvements in immune response and increased levels of haemoglobin, white and red blood cells, albumin, globulin, and total protein for the Triphala dietary groups. In all Triphala dietary groups, the mRNA expression levels of the growth-related (growth hormone (GH) and insulin-like growth factor 1 (IGF-1)) and immune-related genes (cc-chemokine, intereluekin-1β (IL-1β), and intereluekin-8 (IL-8)) were significantly (P < 0.05) upregulated compared to the control groups. After exposure to Saprolegnia ferax infection, the control group exhibited a higher mortality rate (up to 75%) than the Triphala-treated groups. In conclusion, this study demonstrated that dietary inclusion of Triphala at an optimal level of 3% improved the growth performance and immune response of Nile tilapia (Oreochromis niloticus) fingerlings. [ABSTRACT FROM AUTHOR]

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 critical source of seafood production, addressing the global demand for fish products. Suggesting a Deep learning-based classification technique for fishes specifically Indian Major Carp (IMC) as Mrigala, Catla and Rohu is the major objective of this paper along with detecting the disease among them. This world inside hydrosphere has their own discrete living manner. Yet they are not untouched by diseases; fishes mostly affected when young carry pathogens which cause various infections naturally or due to environmental pollutants including chemical and hazardous waste. This paper proposed the classification and prediction of diseases of fishes in aquaculture using Deep Learning based customized Convolutional Neural Network with ResNet-50 model. The proposed model performance metric compared with recent state-of-art techniques. ResNet-50 classifies accurately the IMC and type of disease the fishes are suffering from. [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]

Observations of Black Spot Syndrome (BSS), a pigmented dermatopathy in marine fishes, have been increasingly reported in important grazers such as surgeonfish and parrotfish in the Caribbean. This condition has been linked to infection by the trematode parasite, Scaphanocephalus spp., although relatively little is known about the environmental drivers of infection and how they vary spatially. This study introduces a non-invasive, video-based method to survey BSS presence and severity in ocean surgeonfish (Acanthurus tractus). Application of the approach across 35 coastal sites in Curaçao was used to evaluate the influence of environmental factors on BSS, including longitude, herbivorous fish density, wave energy, depth, nutrient pollution, and inhabited surface area. Of the 5123 fish surveyed between February 2022 and January 2023, 70% exhibited visible signs of BSS, and the average number of lesions per fish increased by ~ fivefold from eastern to western sites along the leeward coastline. Within a site, estimates of BSS severity were broadly consistent between different divers, different reviewers of video footage, and the date of sampling, emphasizing the robustness of the surveillance approach. Analyses of environmental factors indicated that BSS decreased with wave intensity while increasing in association with higher nutrient runoff and fishing pressure. This study provides insight into environmental correlates of BSS severity while highlighting the use of video-based surveillance as a non-invasive survey method. The mechanisms linking environmental factors with BSS as well as its consequences for affected fish remain unknown, emphasizing the need for long-term and experimental studies in this system. [ABSTRACT FROM AUTHOR]

The genus Edwardsiella, previously residing in the family Enterobacteriaceae and now a member of the family Hafniaceae, is currently composed of five species, although the taxonomy of this genus is still unsettled. The genus can primarily be divided into two pathogenic groups: E. tarda strains are responsible for almost all human infections, and two other species (E. ictaluri, E. piscicida) cause diseases in fish. Human infections predominate in subtropical habitats of the world and in specific geospatial regions with gastrointestinal disease, bloodborne infections, and wound infections, the most common clinical presentations in decreasing order. Gastroenteritis can present in many different forms and mimic other intestinal disturbances. Chronic gastroenteritis is not uncommon. Septicemia is primarily found in persons with comorbid conditions including malignancies and liver disease. Mortality rates range from 9% to 28%. Most human infections are linked to one of several risk factors associated with freshwater or marine environments such as seafood consumption. In contrast, edwardsiellosis in fish is caused by two other species, in particular E. ictaluri. Both E. ictaluri and E. piscicida can cause massive outbreaks of disease in aquaculture systems worldwide, including enteric septicemia in channel catfish and tilapia. Collectively, these species are increasingly being recognized as important pathogens in clinical and veterinary medicine. This article highlights and provides a current perspective on the taxonomy, microbiology, epidemiology, and pathogenicity of this increasingly important group. [ABSTRACT FROM AUTHOR]

Eutrophication of aquatic ecosystems is associated with an increased risk of pathogen infection via increased pathogen growth and host exposure via increased pathogen doses. Here, we studied the effect of nutrients on the virulence of an opportunistic bacterial pathogen of fish, Flavobacterium columnare , in challenge experiments with rainbow trout fingerlings. We hypothesized that removing all nutrients by washing the bacteria would reduce virulence as compared to unwashed bacteria, but adding nutrients to the tank water would increase the virulence of the bacterium. Nutrient addition and increase in bacterial dose increased virulence for both unwashed and washed bacteria. For unwashed bacteria, the addition of nutrients reduced the survival probability of fish challenged with low bacterial doses more than for fish challenged with higher bacterial doses, suggesting activation of bacterial virulence factors. Washing and centrifugation reduced viable bacterial counts, and the addition of washed bacteria alone did not lead to fish mortality. However, a small addition of nutrient medium, 0.05% of the total water volume, added separately to the fish container, restored the virulence of the washed bacteria. Our results show that human-induced eutrophication could trigger epidemics of aquatic pathogens at the limits of their survival and affect their ecology and evolution by altering the dynamics between strains that differ in their growth characteristics. [ABSTRACT FROM AUTHOR]

ABSTRACT 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.IMPORTANCEThe 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.

Fish diseases pose a significant threat to food security in aquaculture, as they can lead to considerable reductions in fish production, quality, and profitability. Globally, salmon aquaculture is the quickest-expanding food production system. Detecting and diagnosing fish diseases in their early stages is essential to prevent the spread of diseases and reduce the negative impact on aquaculture's economy and environment. To serve this purpose, we introduce the SalmonScan dataset, a novel and comprehensive collection of images of healthy and infected salmon fish, which can be used for various applications in computer science and aquaculture. Images from online sources and aquaculture salmon firms were gathered to create the dataset. The dataset was then labeled based on the health status of the fish, fresh or infected. Data augmentation methods like rotation, cropping, flipping, and scaling were used to guarantee the dataset's strength and size. The dataset includes 456 images of fresh fish and 752 images of infected fish, both varied and inclusive while maintaining excellent quality. Other researchers and practitioners can use the dataset we have collected for various purposes. They can use it to create and test new or existing machine learning (ML) and deep learning (DL) based computer vision models for identifying, categorizing, counting, and analyzing the behavior and biomass of salmon fish. They can also use it to study how different environmental factors affect the health and growth of salmon fish. Furthermore, they can evaluate the accuracy and performance of different image acquisition and processing methods. Additionally, they can explore the feasibility of using generative adversarial networks (GANs) and transfer learning to improve the training speed and stability of DL models designed for fish detection. This SalmonScan dataset paper describes and documents the dataset in detail, making it publicly available and reusable for the research community.

In the field of aquaculture, bacterial pathogens pose significant challenges to fish health and production. Advancements in genomic technologies have revolutionized our understanding of bacterial fish pathogens and their interactions with their host species. This review explores the application of genomic approaches in the identification, classification, and characterization of bacterial fish pathogens. Through an extensive analysis of the literature, we have compiled valuable data on 79 bacterial fish pathogens spanning 13 different phyla, encompassing their whole genome sequences. By leveraging high-throughput sequencing techniques, researchers have gained valuable insights into the genomic makeup of these pathogens, enabling a deeper understanding of their virulence factors and mechanisms of host interaction. Furthermore, genomic approaches have facilitated the discovery of potential vaccine and drug targets, opening up new avenues for the development of effective interventions against fish pathogens. Additionally, the utilization of genomics in fish disease resistance and control in aquaculture has shown promising results, enabling the identification of genetic markers associated with disease resistance traits. This review highlights the significant contributions of genomics to the field of fish pathogen research and underscores its potential for improving disease management strategies and enhancing the sustainability of aquaculture practices. [ABSTRACT FROM AUTHOR]

Simple Summary: The development of the production of freshwater species such as Nile tilapia has favored the increase in larger-scale infectious outbreaks and new diseases in this industry. This work aimed to determine the presence of bacterial diseases in Nile tilapia cultured in Chiapas, Mexico. Blood and viscera samples were taken from healthy and sick animals from several commercial farms. The isolated bacteria were identified and characterized by different laboratory tests. The isolation, identification and characterization of two pathogens involved in an infectious process were achieved: Staphylococcus haemolyticus and Providencia vermicola. Both bacteria were cataloged as causal agents of diseases in tilapia farming in Mexico. This is the first report of bacterial diseases in tilapia farms caused by two rare but potentially emerging pathogens for the species. These results make it possible to know the health situation of the region, estimate economic losses, know the behavior of pathogens and propose effective prevention and control measures. This work aimed to determine the presence of bacterial pathogens in fish with a clinical picture suggestive of infectious disease in Nile tilapia reared in Chiapas, Mexico. Blood and viscera samples were taken from healthy and diseased animals from commercial farms. Clinical and pathological examinations of each individual were performed and samples were collected for bacteriological studies. The bacterial isolates were identified and characterized by culture, biochemical tests, antibiogram, challenge tests and 16S rRNA sequencing. Staphylococcus haemolyticus and Providencia vermicola were isolated from various diseased organisms. The clinical picture caused by Staphylococcus haemolyticus was characterized by appetite disorders, neurological signs, nodulation or ulceration in different areas and congestion or enlargement of internal organs. Providenciosis in juvenile specimens caused a characteristic picture of hemorrhagic septicemia. Challenge tests performed in healthy organisms revealed that both infections caused higher mortality rates in fish (p < 0.05) compared with non-infected specimens, with 100% survival. There was 100% mortality for animals infected with P. vermicola after three days post infection and 45% for those infected with S. haemolyticus. The isolation and identification of two pathogens involved in an infection process were achieved and cataloged as potential causal agents of disease outbreaks in tilapia farming in Mexico. This is the first report of possible bacterial infection caused by S. haemolyticus and P. vermicola in tilapia farms, which are two uncommon but potentially emerging pathogens for the species. [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 recent years, the field of emerging computer vision systems has witnessed significant advancements in automated disease diagnosis through the utilization of vision-oriented technology. This article proposes an optimal approach for detecting the presence of ailments in Rohu fish. The aims of our research is to identify the most significant features based on Analysis of Variance (ANOVA) feature selection and evaluate the best performance among all features for Rohu fish disease recognition. At the outset, diverse techniques for image preprocessing were employed on the acquired images. The region affected by the disease was partitioned through utilization of the K-means clustering algorithm. Subsequently, 10 distinct statistical and Gray-Level Co-occurrence Matrix (GLCM) features were extracted after the image segmentation. The ANOVA feature selection technique was employed to prioritize the most significant features N (where 5 ≤ N ≤ 10) from the pool of 10 categories. The Synthetic Minority Oversampling Technique, often known as SMOTE, was applied to solve class imbalance problem. After conducting training and testing on nine different machine learning (ML) classifiers, an evaluation was performed to estimate the performance of each classifier using eight various performance metrics. Additionally, a receiver operating characteristic (ROC) curve was generated. The classifier that utilized the Enable Hist Gradient Boosting algorithm and selected the top 9 features demonstrated superior performance compared to the other eight models, achieving the highest accuracy rate of 88.81%. In conclusion, we have demonstrated that the feature selection process reduces the computational cost.

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]

Cantang grouper (Epinephelus sp.) is a fish with a high economic value and has been widely cultivated. VNN disase, caused by Betanodavirus infection, can lead to mass mortality of cantang grouper. Precautions considered effective in preventing Viral nervous necrosis (VNN) disease include vaccination. This study aimed to determine the effect of administering recombinant Chlorella vulgaris protein nanovaccine based on chitosan hybrid nanoparticles in increasing the immune response of cantang grouper infected with VNN. The study consisted of five treatments: K+ (cantang grouper infected with VNN), K- (healthy cantang grouper), T1 (healthy cantang grouper given 33 µl of nanovaccine and then challenged with VNN), T2 (healthy cantang grouper given 66 µl of nanovaccine and then tested with a VNN challenge), and T3 (healthy cantang grouper given 112 µl of nanovaccine and then tested with a VNN challenge). The parameters observed were haematology, nanovaccine Relative percent survival (RPS), and Survival rate (SR) levels. The study results showed that administering the nanovaccine increased the immune response of the fish, as indicated by an increase in haematology response, RPS, and SR in cantang grouper compared to the treatment without nanovaccine administration. The best dose of nanovaccine in this study is 33 µl. [ABSTRACT FROM AUTHOR]

The naked characin (Gymnocharacinus bergii) is the only endemic fish of the arid Patagonia of Argentina, living only in the thermal headwaters of the Valcheta Stream in the Somuncura Plateau. This species is listed as Critically Endangered on the IUCN Red List.In April 2018, a massive mortality event was observed in the species. Parasitological studies identified the cause as an epidemic of white spot disease, caused by the parasite Ichthyophthirius multifiliis (Ich).Ich is a common disease in aquaculture settings, but it has also been reported as an epizootic in wild fish populations across tropical and temperate regions worldwide. This occurrence is associated with the introduction of fish into non‐native environments.This article presents the first recorded instance of a mass mortality event and Ich outbreak in the naked characin. It includes a mapping of the disease in the headwaters of the stream, an estimation of the impact on the species' population size, and an analysis of potential causes associated with this epidemic.The results indicate that the epizootic produced mortality of 82% of the global population of the naked characin and was linked to the presence and high abundances of the invasive fish species Uruguay tetra (Cheirodon interruptus). The disease occurred in stream sectors where both characid species coexist, particularly in areas with the highest water temperatures.The Ich outbreak represents the most recent and severe threat recorded for the Critically Endangered naked characin. Implementing control measures against the invasive Uruguay tetra is imperative to prevent future outbreaks that could push the species to the brink of extinction in the near future.This study provides crucial information for assessing current management interventions and developing new strategies within the framework of the action plan for naked characin conservation. [ABSTRACT FROM AUTHOR]

The continuity of antimicrobial resistance development in bacteria changes the type and dose of effective antibiotic treatments and makes routine monitoring studies necessary for successful control of bacterial diseases. This study was aimed to determine the current antibiotic susceptibility of Lactococcus garvieae, which causes significant economic losses in rainbow trout (Oncorhynchus mykiss) farms. In the study, two consecutive visits were made to three farms operating on the banks of a stream during a disease outbreak in the fall of 2018. At each visit, 10 fish showing the signs of disease from each farm (60 fish in total) were sampled and L. garvieae was isolated from 16 fish. All isolates were identified using conventional and molecular methods. Then, they were examined for 5 different antibiotic resistance genes and their antibiotic susceptibility profiles were determined using the Kirby Bauer disc diffusion technique. Results of the disc diffusion test revealed that all 16 isolates had a different antibiotic susceptibility profile and the isolates with different antibiotic susceptibility profile could exist within and between farms, using the same water source. Furthermore, they revealed that highly resistant isolates that showed no susceptibility up to 82 to 100% of the 33 antibiotics at the doses evaluated exist in all farms. All isolates carried either tetA or tetB genes or both and the majority of isolates carried tetA gene. Together with this, 25% of the isolates which carried both or one of the resistance genes showed susceptibility to all 4 tetracycline class antibiotics at the doses evaluated. Results of the study and their comparison with previous studies in the same production area or in different regions of the country revealed the dynamic nature of antibiotic resistance development in L. garvieae. Additionally, it showed that monitoring studies with a limited number of isolates may not give an accurate picture of the current status of antibiotic resistance from a production area. These results of the study were also discussed in terms of the treatment strategies that trout farmers should follow when treating lactococcosis.

The genus Edwardsiella, previously residing in the family Enterobacteriaceae and now a member of the family Hafniaceae, is currently composed of five species, although the taxonomy of this genus is still unsettled. The genus can primarily be divided into two pathogenic groups: E. tarda strains are responsible for almost all human infections, and two other species (E. ictaluri, E. piscicida) cause diseases in fish. Human infections predominate in subtropical habitats of the world and in specific geospatial regions with gastrointestinal disease, bloodborne infections, and wound infections, the most common clinical presentations in decreasing order. Gastroenteritis can present in many different forms and mimic other intestinal disturbances. Chronic gastroenteritis is not uncommon. Septicemia is primarily found in persons with comorbid conditions including malignancies and liver disease. Mortality rates range from 9% to 28%. Most human infections are linked to one of several risk factors associated with freshwater or marine environments such as seafood consumption. In contrast, edwardsiellosis in fish is caused by two other species, in particular E. ictaluri. Both E. ictaluri and E. piscicida can cause massive outbreaks of disease in aquaculture systems worldwide, including enteric septicemia in channel catfish and tilapia. Collectively, these species are increasingly being recognized as important pathogens in clinical and veterinary medicine. This article highlights and provides a current perspective on the taxonomy, microbiology, epidemiology, and pathogenicity of this increasingly important group.

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.

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]

The continuity of antimicrobial resistance development in bacteria changes the type and dose of effective antibiotic treatments and makes routine monitoring studies necessary for successful control of bacterial diseases. This study was aimed to determine the current antibiotic susceptibility of Lactococcus garvieae, which causes significant economic losses in rainbow trout (Oncorhynchus mykiss) farms. In the study, two consecutive visits were made to three farms operating on the banks of a stream during a disease outbreak in the fall of 2018. At each visit, 10 fish showing the signs of disease from each farm (60 fish in total) were sampled and L. garvieae was isolated from 16 fish. All isolates were identified using conventional and molecular methods. Then, they were examined for 5 different antibiotic resistance genes and their antibiotic susceptibility profiles were determined using the Kirby Bauer disc diffusion technique. Results of the disc diffusion test revealed that all 16 isolates had a different antibiotic susceptibility profile and the isolates with different antibiotic susceptibility profile could exist within and between farms, using the same water source. Furthermore, they revealed that highly resistant isolates that showed no susceptibility up to 82 to 100% of the 33 antibiotics at the doses evaluated exist in all farms. All isolates carried either tetA or tetB genes or both and the majority of isolates carried tetA gene. Together with this, 25% of the isolates which carried both or one of the resistance genes showed susceptibility to all 4 tetracycline class antibiotics at the doses evaluated. Results of the study and their comparison with previous studies in the same production area or in different regions of the country revealed the dynamic nature of antibiotic resistance development in L. garvieae. Additionally, it showed that monitoring studies with a limited number of isolates may not give an accurate picture of the current status of antibiotic resistance from a production area. These results of the study were also discussed in terms of the treatment strategies that trout farmers should follow when treating lactococcosis. [ABSTRACT FROM AUTHOR]

The gut microbiota is currently one of the most studied 'organs' in animals, and fish are no exception. A complex diversity of microbes, including bacteria, archaea, yeast and fungus, constitute the gut microbiota, creating a complex interaction with their host and accomplishing multiple beneficial functions, such as food digestion, nutrient absorption, immune system, endocrine and stress response. The microbiota–pathogen interaction protects the host by mounting colonization resistance, competing for nutrients and space. Changes in the balance of the microbiota community could affect their structure and homeostasis, inducing dysbiosis. In addition, invading pathogens can induce dysbiosis by evading the host's defence barriers, acquiring nutrients from the fish host, using metabolites produced by the microbiota and producing toxins. In this regard, understanding the interactions within the fish gut microbiota is essential to prevent pathogen establishment in the host. Hence, this review describes the close and indivisible relationships and interactions between gut microbiota and pathogens that could lead to dysbiosis and disease. [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.

Indonesia become a maritime country with large of ocean area and beach line with marine species diversity reaches 37% of the world’s fish. This makes Indonesia have aquaculture potential that supported by an appropriate climate. However, the challenge of viral diseases caused by Infectious Spleen and Kidney Necrosis Virus (ISKNV) and Viral Nervous Necrosis (VNN) would hamper marine aquaculture and causing huge economic losses. Therefore, it is necessary to carry out early detection methods that are efficient, fast, precise and accurate to identifying these viral disease. Here we developed a multiplex-PCR (mPCR) a method that can detect simultaneously of the ISKNV and VNN. The results of this method showed high sensitivity and specificity by using MCP and CP gene target primers to detect ISKNV and VNN, respectively. From a total of 353 samples of seawater fish examined by mPCR, positive results following of single infection of ISKNV and VNN were 14 and 2, respectively. We also found that 18 grouper fish was co-infection with these viruses. From these results, it shows that the mPCR method developed has efficiency, faster and high accuracy. This founding was possible to be applied in laboratory testing or early detection system in the field for ISKNV and VNN.

The demand for freshwater ornamental fish as anti-stress pets and a source of livelihood had become popular in Puerto Princesa City (PPC), Palawan during the surge of COVID-19. However, the occurrence of many health-related issues become a major problem due to a lack of experience and knowledge of some fish owners engaged in freshwater ornamental fish keeping and breeding methods. This study was conducted on 13 local fish owners to determine the common diseases in freshwater ornamental fishes, affected species and their life stages and the treatments and preventive measures. A total of 19 diseases were recorded infecting the freshwater ornamental fishes in PPC. White-spot or ich disease was the most prominent disease, followed by tail and fin rot. Juvenile and adult of goldfish (Carassius auratus), Siamese fighting fish (Betta splendens) and guppy (Poecilla reticulata) were the most infected fishes, observed by 1 (7.7%) to 5 (38.5%) fish hobbyist. The salt bath was the most common treatment applied. Measures to increase the awareness of local fish hobbyist in terms of fish handling, breeding and health management is highly suggested to continuously improve and expand this developing fishery in Palawan as a source of income and pet companion.

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]

This work aimed to determine the presence of bacterial pathogens in fish with a clinical picture suggestive of infectious disease in Nile tilapia reared in Chiapas, Mexico. Blood and viscera samples were taken from healthy and diseased animals from commercial farms. Clinical and pathological examinations of each individual were performed and samples were collected for bacteriological studies. The bacterial isolates were identified and characterized by culture, biochemical tests, antibiogram, challenge tests and 16S rRNA sequencing. Staphylococcus haemolyticus and Providencia vermicola were isolated from various diseased organisms. The clinical picture caused by Staphylococcus haemolyticus was characterized by appetite disorders, neurological signs, nodulation or ulceration in different areas and congestion or enlargement of internal organs. Providenciosis in juvenile specimens caused a characteristic picture of hemorrhagic septicemia. Challenge tests performed in healthy organisms revealed that both infections caused higher mortality rates in fish (p < 0.05) compared with non-infected specimens, with 100% survival. There was 100% mortality for animals infected with P. vermicola after three days post infection and 45% for those infected with S. haemolyticus. The isolation and identification of two pathogens involved in an infection process were achieved and cataloged as potential causal agents of disease outbreaks in tilapia farming in Mexico. This is the first report of possible bacterial infection caused by S. haemolyticus and P. vermicola in tilapia farms, which are two uncommon but potentially emerging pathogens for the species.

In the food production field, aquaculture is the fastest growing sector, becoming an important source of protein production according to FAO report. Romania has a legacy in pond aquaculture production and the total estimated produced fish biomass is aproximatelly 10 000 tones per year. In order to ensure economic efficiency and sustainability through the reduction of fish mortality, disease management and control is imperative. The South-East Region of Romania is characterized by the practice of aquaculture in extensive production systems, such as pond. The pond aquaculture systems in the South-East of Romania is supplied with water from the hydrographycal basin of Danube River. The purpose of this study is to assess disease status on 3 different fish populations from the South-East Region of Romania and identify differences in disease clinical signs. The biological material (carp, silver carp, bighead carp, prussian carp) was collected by control harvesting from 3 different aquaculture pond units. Fish were transported to the ichthyopathology laboratory at the Institute of Research and Development for Aquatic Ecology, Fishing and Aquaculture of Galati and analyses were carried out. All studied populations presented seasonal specific disease signs that may cause mortality in fish population between the range of 20 and 80%. A decrease of fish mortality rate can be obtained by early diagnostic establishment and fast treatment application. In order to avoid the occurrence of the bioresistence phenomenon administration of antibiotic substances should be administrated exclusivelly in case of secundary bacterian infection and following a antibiogram test.

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]

Simple Summary: The automatic diagnosis of fish diseases is an important task in smart aquaculture, and plays a key role in detecting fish conditions, understanding disease signs, and improving fish welfare and health. This paper reviews the latest advances in intelligent fish disease diagnosis techniques for aquatic applications. To acquire high-quality images to improve the accuracy of fish disease diagnosis, the paper reviews, in the second paragraph, how image-processing techniques can be used to acquire high-quality images. The third paragraph of this paper reviews the methods of intelligent fish disease diagnosis, including expert system detection, camera image detection, microscope image detection, spectral image detection, fluorescence image detection, ultrasonic image detection, and sensor detection methods. Additionally, the advantages and disadvantages of each detection method are summarized, including whether they cause damage to the fish body. Finally, we put forward the prospect of the intelligent detection of fish diseases and summarize the methods that may be used in the intelligent diagnosis of fish disease. Aquatic products, as essential sources of protein, have attracted considerable concern by producers and consumers. Precise fish disease prevention and treatment may provide not only healthy fish protein but also ecological and economic benefits. However, unlike intelligent two-dimensional diagnoses of plants and crops, one of the most serious challenges confronted in intelligent aquaculture diagnosis is its three-dimensional space. Expert systems have been applied to diagnose fish diseases in recent decades, allowing for restricted diagnosis of certain aquaculture. However, this method needs aquaculture professionals and specialists. In addition, diagnosis speed and efficiency are limited. Therefore, developing a new quick, automatic, and real-time diagnosis approach is very critical. The integration of image-processing and computer vision technology intelligently allows the diagnosis of fish diseases. This study comprehensively reviews image-processing technology and image-based fish disease detection methods, and analyzes the benefits and drawbacks of each diagnostic approach in different environments. Although it is widely acknowledged that there are many approaches for disease diagnosis and pathogen identification, some improvements in detection accuracy and speed are still needed. Constructing AR 3D images of fish diseases, standard and shared datasets, deep learning, and data fusion techniques will be helpful in improving the accuracy and speed of fish disease diagnosis. [ABSTRACT FROM AUTHOR]

Fish plays a significant role in food and nutritional security in our country as well as the whole world. Owing to this reason, it becomes essential to increase the production of fish. But it is diminishing due to numerous diseases which can deteriorate the national economy. It is a fact that there is no single effective research work that has been done in regards to fish disease due to a lack of data and a high level of expertise. Consequently, our aim is to recognize the fish disease effectively that can help the remote farmers who need proper support for fish farming. Recognition of disease-attacked fish at an early stage can help us take necessary steps to prevent from spreading of the disease. In this work, we have performed an in-depth analysis of expert systems that can continue with an image captured with the help of smartphones and identifies the disease. Two set of features is selected then a segmentation algorithm is employed to detect the disease attacked portion from the disease-free portion. Furthermore, eight prominent classification algorithms are implemented accordingly to measure the performance using performance evaluation matrices. The achieved accuracy of Random forest 88.87% which is promising enough. [ABSTRACT FROM AUTHOR]

Highlight Research: • It has been found that many fish died with wounds from farmers in Blitar, Indonesia. • The mucosal smear test from mucosal gills of C. carpio infected with Myxobolus. • In the blood smear test of C. carpio, there was no myxobolus found in the blood. • In gill organ testing using SEM that Myxobolus is found in gills (C. carpio). • The shape of Myxobolus resembles an imperfect ball with a hollow in the middle. Abstract The biggest problem that is often considered to be an obstacle to Common carp culture is the emergence of disease attacks. One type of disease that often attacks the seeds of Cyprinus carpio is Myxobolus (a systemic parasite that can cause harm to fish farming). The aim of this study was to determine the molecular expression through the smear test on C. carpio gills, to determine the image of the gill organs of C. carpio using the SEM test, and to determine the description of the spores of Myxobolus sp. Data were analyzed using descriptive methods. Descriptive method used was comparative descriptive comparing molecular expression in the test of gill mucosal smear of fish using a light microscope and gill organ testing using Scanning Electron Microscope (SEM) on C. carpio infected by Myxobolus sp. In this study, the results showed that in C. carpio infected with true Myxobolus found the presence of Myxobolus in the mucosal smear test and SEM test on gill tissue, but not found in the blood smear test.

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]

Yersiniosis, caused by the fish pathogen Yersinia ruckeri, is a serious bacterial septicaemia affecting mainly salmonids worldwide. The acute infection may result in high mortality without apparent external disease signs, while the chronic one causes moderate to considerable mortality. Survivors of yersiniosis outbreaks become carriers. Y. ruckeri is able to adhere to, and to invade, phagocytic and non-phagocytic fish cells by using unknown molecular mechanisms. The aim of this study was to describe the kinetics of cell invasion by Y. ruckeri serotype O1 biotype 1 in a fish cell line (RTG-2) originating from rainbow trout gonads. The efficiency of invasion by Y. ruckeri was found to be temperature dependent, having a maximum at 20 °C. The bacterium was able to survive up to 96 h postinfection. The incubation of the cells at 4 °C and the pre-incubation of the bacteria with sugars or heat-inactivated antiserum significantly decreased the efficiency of invasion or even completely prevented the invasion of RTG-2 cells. These findings indicate that Y. ruckeri is capable of adhering to, entering and surviving within non-phagocytic cells, and that the intracellular environment may constitute a suitable niche for this pathogen that can favour the spread of infection and/or the maintenance of a carrier state of fish. [ABSTRACT FROM AUTHOR]