We are pleased to present the first collection dedicated to highlighting the research of our Editorial Board, entitled Editors' Showcase: Disease and Health Management. This exclusive collection is open to Editorial Board members only and will feature high-quality contributions from our Associate and Review Editors. Specialty Chief Editor, Prof. Beatriz Novoa, leads this initiative which will focus on new insights, novel developments, current challenges, latest discoveries, recent advances, and future perspectives in the field of Disease and Health Management. The work presented here celebrates the broad diversity of research performed across the section and aims to put a spotlight on all areas of interest to our Editors. This collection aims to further support Frontiers’ strong community by recognizing and promoting the work of highly deserving Editors.

Institute of Marine Research, Spanish National Research Council (CSIC)

Frontiers in Aquaculture

Disease and Health Management

Editors' Showcase: Disease and Health Management

Aquaculture, the farming of aquatic organisms, stands as a crucial industry, providing a significant global source of seafood. As the world&#x2019;s population continues to grow, the demand for protein-rich food sources rises in tandem. However, the susceptibility of aquatic animals to diseases poses a constant threat, potentially leading to substantial economic losses.The World Organisation for Animal Health (WOAH) identifies key pathogens affecting aquatic animals, commonly referred to as &#x201c;listed diseases&#x201d;. These diseases have a severe impact on aquatic animals, prompting the establishment of international standards and guidelines by WOAH to manage and control their spread. In addition to these listed diseases, there are other relevant or emerging diseases causing mortalities in various fish and shellfish species worldwide. Efficient diagnostic tools for regular monitoring and early pathogen detection are crucial. These tools, along with preventive measures like vaccination programs, play a pivotal role in disease management.Nevertheless, a comprehensive approach is essential, integrating these elements with good husbandry practices. This includes maintaining balanced nutrition, ensuring optimal water quality, and engaging in selective breeding for disease resistance. This holistic strategy aims to mitigate the impact of diseases on aquaculture operations.&#x201d;Health is a critical aspect of aquaculture because diseases can lead to significant economic losses. Efficient diagnostic tools that allow to identify the pathogens in regular monitoring and early detection have to be combined with preventive measures that include vaccination programs to protect aquatic animals from specific diseases. However, a holistic approach that combines these elements with good husbandry practices including an adequate nutrition (balanced and nutritious diets), optimal water quality, selective breeding for disease resistance, should be applied to mitigate the impact of diseases in aquaculture.Continuous research and innovation play a vital role in improving the overall health and sustainability of aquaculture operations. It is important to consider not only complex research innovations but other solutions based in common sense that are effective ways to fight diseases avoiding the spread of pathogens.In this Research Topic, we have a collection of several articles pointing out some key aspects related to aquatic animal health that are not usually taken into account. As the review from <a href="https://doi.org/10.3389/faquc.2023.1254038">Elvevoll et al.</a> reports, we need to understand food safety practices and nutritional content of fish that are increasingly demanded by the society. It emphasizes the importance of sustainable food security and improved nutrition for global well-being, highlighting the environmental and health challenges associated with land-based food production. A sustainable production of aquatic food focused in good aquaculture practices, biosecurity measures and infection management, will result in a healthy seafood consumption.One example of the effect of aquaculture products on human health is the use of antibiotics. While antibiotics can be effective in controlling diseases in aquaculture, their use raises concerns about the development of antibiotic resistance in bacteria. This resistance can have adverse effects on both aquatic and human health, as antibiotic-resistant bacteria may spread through the food chain. To address these concerns, there is an ongoing effort in the aquaculture industry to promote responsible antibiotic use and find alternative disease management strategies. This includes improving overall farm management practices, implementing better biosecurity measures, and exploring the use of probiotics and vaccines as alternatives to antibiotics. Sustainable and responsible aquaculture practices aim to balance the need for disease control with minimizing the potential environmental and health risks associated with antibiotic use in aquaculture. <a href="https://doi.org/10.3389/faquc.2023.1201466">Kumari et&nbsp;al.</a> research focuses on optimizing bacteriophage cocktails for freshwater fish infections, demonstrating their efficacy in saving fish and highlighting their potential as alternatives to antibiotics. They propose Phage-based treatments as viable alternatives to antibiotics in aquaculture. These approaches provide targeted specificity, reduce the risk of antibiotic resistance, are environmentally friendly, and allow for customization based on the specific bacteria causing infections. Despite these advantages, challenges exist, such as the need to carefully match the specific phages to the targeted bacteria and address issues related to phage stability and delivery. Ongoing research and development in phage therapy for aquaculture aim to overcome these challenges and establish it as a sustainable and effective alternative to traditional antibiotic use in the industry.<a href="https://doi.org/10.3389/faquc.2023.1169149">Patanasatienkul et al.</a> concentrate on the biosecurity measures adopted by shrimp farmers in Indonesia. Infectious diseases outbreaks are influenced by various factors related to hosts, the environment, and husbandry practices. Effectively managing farms helps decrease the likelihood of introducing harmful pathogens to a farming site. This should be the first preventive method to fight diseases. If the introduction of pathogens cannot be prevented, addressing the factors that facilitate their spread within farms helps minimize the potential impact on shrimp health, mortality, and subsequent economic losses. It is crucial to recognize that biosecurity practices exert a direct and measurable influence on the occurrence and transmission of pathogens within and among farms that significantly impacts the overall productivity of the facility.<a href="https://doi.org/10.3389/faquc.2023.1125595">Elsheshtawy et&nbsp;al.</a> investigate the impact of in situ net cleaning on the gill health of Atlantic salmon and rainbow trout, revealing diverse fouling species and changes in water quality. Concerns include potential negative effects on fish health and farm infrastructure. Although only moderate changes in gill inflammatory and antigen presentation activity was observed, a significant change happened in the gill microbiome induced a decreased bacterial richness and decreased diversity. Also, biofouling organisms may act as transient reservoirs for some fish pathogens. With all these results, the authors suggest that changes in gill microbiome could be related to the host stress response to the process of net cleaning and could be indicative of increased mortalities post-cleaning. Microbial dysbiosis or the imbalance of the normal microbial communities of the gills of cultured aquatic species can have negative consequences for the cultured fish since gills play a crucial role in respiration, osmoregulation, and immune defense in fish and other aquatic organisms. Therefore, the use of non-lethal gill microbiome assessments in parallel to standard pathogen monitoring throughout the marine cycle may have potential as a refined health management tool.In summary, aquaculture, faces several challenges related to health and sustainability. Addressing these challenges is crucial for the long-term success of the industry. Some of the key challenges for aquaculture health include a) controlling the spread of pathogens implementing effective biosecurity measures and developing efficient and fast diagnosis tools, b) developing effective vaccines against the main aquaculture diseases, c) Maintaining optimal conditions in the farms concerning water quality or sustainable and healthy diets. Efforts to address these challenges require collaboration among researchers, industry stakeholders, and policymakers to develop and implement sustainable and responsible aquaculture practices.Efforts are being made globally to address these challenges through research, technological innovation, improved management practices, and international collaboration to promote sustainable and responsible aquaculture. This includes the development of alternative feed sources, advancements in disease management, and the promotion of environmentally friendly and socially responsible aquaculture practices.BN: Writing &#x2013; original draft, Writing &#x2013; review &amp; editing.The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Editorial: Editors’ showcase: disease and health management

Food agencies recommend increased consumption of aquatic food in the diet to promote healthy living and sustainability, particularly to prevent Western lifestyle-related diseases and secure sustainable food systems. This requires growth in global seafood production, and the utilization of low trophic species (LTS) is suggested. LTS are already considered nutritious and important in Asian and Pacific diets.  As the use of LTS is expanding in Western diets, producers and consumers need information on food safety and nutritional contribution. LTS are mainly immobile or slow-moving extractive species or organisms feeding on such, and their nutrient and contaminant content varies by species and location. Species-specific knowledge on nutritional contents and safe consumption limits are often missing, making monitoring and analysis of contaminants, nutrients, and consumption data crucial to guide the utilization and consumption of LTS. Using global and regional standards regarding nutrients, food hazards, and labeling, this review highlights appropriate guidelines and regulations to guide the utilization of selected novel species and identifies knowledge gaps. 

Food agencies recommend increasing the consumption of aquatic food to promote healthy living and sustainability, and, particularly, to prevent Western lifestyle-related diseases and secure sustainable food systems. This requires growth in global seafood production, and the utilization of low trophic species (LTS) is suggested. LTS are already considered nutritious and important in Asian and Pacific diets. As the use of LTS is expanding in Western diets, producers and consumers need information on the food safety practices associated with them and their nutritional content. LTS are mainly immobile or slow-moving extractive species or organisms that feed on such, and their nutrient and contaminant content varies by species and location. Species-specific knowledge on nutritional contents and safe consumption limits is often missing, making the monitoring and analysis of contaminants, nutrients, and consumption data crucial to guiding the utilization and consumption of LTS. Using global and regional standards regarding nutrients, food hazards, and labeling, this review highlights the appropriate guidelines and regulations for guiding the utilization of selected novel species and also identifies knowledge gaps.

New marine low trophic resources as food: nutritional and food safety aspects

Current information on biosecurity measures implemented by shrimp farmers in Indonesia is limited. This study describes farmer demographic characteristics, on-farm biosecurity practices, farm production and disease status, among small and medium holder shrimp farms on Java Island, Indonesia. A questionnaire-based survey was conducted from November 2019 to May 2020 to collect data from shrimp farms operating in various regions of the Java Island. A numerical score was assigned for each of the assessed biosecurity practices, based on whether it was a conventional risk factor or a protective factor.  Based on responses from 90 shrimp farmers, who volunteered to participate in the study, mean overall biosecurity scores ranged from 32 to 54 (out of a maximum score of 100). Most farms (88.9%) either shared common water sources with other aquaculture farms or were connected to other farms via water channel. Farm equipment sharing was common both within (91.1%) and between (41%) farms. Water pre-treatment was common (99%), but approximately a third of the farms did not practice any routine quality assessment for post larvae before stocking. On average, farms produced 1.6 kg/m2 (95% CI: 1.2, 2.0) of shrimp with a harvest size of 43 shrimp/kg (95% CI: 37, 49) or an average weight of 23.3 g at time of harvest. An increasing trend in harvest weight per pond area and shrimp size at harvest was noted with increasing overall biosecurity score. These results indicated that farms with better biosecurity practices tended to have a higher production yield.

Current information on biosecurity measures implemented by shrimp farmers in Indonesia is limited. This study describes farmer demographic characteristics, on-farm biosecurity practices, farm production and disease status, among small and medium holder shrimp farms on Java Island, Indonesia. A questionnaire-based survey was conducted from November 2019 to May 2020 to collect data from shrimp farms operating in various regions of the Java Island. A numerical score was assigned for each of the assessed biosecurity practices, based on whether it was a conventional risk factor or a protective factor. Based on responses from 90 shrimp farmers, who volunteered to participate in the study, mean overall biosecurity scores ranged from 32 to 54 (out of a maximum score of 100). Most farms (88.9%) either shared common water sources with other aquaculture farms or were connected to other farms via water channel. Farm equipment sharing was common both within (91.1%) and between (41%) farms. Water pre-treatment was common (99%), but approximately a third of the farms did not practice any routine quality assessment for post larvae before stocking. On average, farms produced 1.6 kg/m2 (95% CI: 1.2, 2.0) of shrimp with a harvest size of 43 shrimp/kg (95% CI: 37, 49) or an average weight of 23.3 g at time of harvest. An increasing trend in harvest weight per pond area and shrimp size at harvest was noted with increasing overall biosecurity score. These results indicated that farms with better biosecurity practices tended to have a higher production yield.

Survey of farm management and biosecurity practices on shrimp farms on Java Island, Indonesia

Introduction: The present study aimed to optimize the doses and schedule of specific bacteriophage cocktails in freshwater fish infections as prophylactic and therapeutic measures.   Methods: The three most active phages against Aeromonas hydrophila (φAHBHU12, φAHBHU16, and φAHBHU19) were characterized phenotypically and genotypically. Intramuscular and oral routes were used for the lethal dose 100 (LD100) of A. hydrophila and were determined in Pangasius buchanani. The phage therapy was given simultaneously and after 6, 12 and 24 hours of bacterial challenge through intramuscular and oral routes. Results: The prophylactic and early phage administration could save the fish. Further, the dose of intramuscular 1.0×104 PFU/fish and oral 1.0×106 PFUmL-1 of the phage cocktail was optimal.  Discussion: The efficacy of bacteriophage therapy as preventive or curative measures practical when administered simultaneously or early hours of A. hydrophila infection in aquaculture systems. Phage-based approaches may be used as an alternative to antibiotics in aquaculture to reduce antibiotic use as a part of the One Health approach.

Introduction: The present study aimed to optimize the doses and schedule of specific bacteriophage cocktails in freshwater fish infections as prophylactic and therapeutic measures.Methods: The three most active phages against Aeromonas hydrophila (A. hydrophila) (φAHBHU12, φAHBHU16, and φAHBHU19) were characterized phenotypically and genotypically. Intramuscular and water immersion routes were used to calculate the absolute lethal dose of A. hydrophila in Pangasius buchanani. Phage therapy was given simultaneously and after 6, 12, and 24&nbsp;h of bacterial challenge through intramuscular and water immersion routes.Results: The prophylactic and early phage administration could save the fish. Furthermore, the dose of intramuscular 1.0&nbsp;×&nbsp;104 plaque-forming unit (PFU)/fish and water immersion 1.0&nbsp;×&nbsp;106 PFU mL–1 of the phage cocktail was optimal.Discussion: The efficacy of bacteriophage therapy as preventive or curative measures practical when administered simultaneously or early hours of A. hydrophila infection in aquaculture systems. Phage-based approaches may be used as an alternative to antibiotics in aquaculture to reduce antibiotic use as a part of the “One Health” approach.

Evaluation of bacteriophage therapy of Aeromonas hydrophila infection in a freshwater fish, Pangasius buchanani

Net biofouling is a crucial obstacle for the global salmon industry in seawater grow-out stage. Current mitigation of net biofouling occurs primarily through the regular removal of biofouling using in situ cleaning. While in situ net cleaning is effective there is uncertainty as to whether the equipment or disposed material has a negative impact upon fish health. The significant surface area and direct contact with the environment leaves the gill and its associated microbiome especially exposed to such concerns. This study aimed to provide a detailed understanding of the impact of in situ net cleaning on Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) gill health. Three field trials were conducted on commercial farms producing salmon and trout in western Norway. Fouling organisms on net pens and flushed particles during in situ cleaning were identified and screened for major fish pathogens. Hydrographic profile measurements were performed during net cleaning to measure the impact on water quality. Gill samples were collected before and after in situ cleaning and examined for histopathological changes, inflammatory responses and the prevalence of major pathogens. 16S rRNA amplicon sequencing was employed to explore the impact of net cleaning on the gill microbial community. Data obtained identified a diversity of fouling species including hydroids, algae, skeleton shrimps, and filter feeders (bryozoan, blue mussel), a direct impact on measured water quality indicators, a moderate change in gill inflammatory and antigen presentation activity and a large significant change in the gill microbial community. Observed changes in the gill microbiome involve decreased bacterial richness coupled to an increase in identified bacterial genera that are related to negative health consequences. Parallel analyses for pathogen load in biofouling organisms and flushed particles highlighted the presence of several fish bacteria and parasites. However, minor changes were detected in salmon gill pathogen diversity and load. Our results suggest that biofouling organisms may act as transient reservoirs for some fish pathogens but not viruses and the gill microbial dysbiosis could be related to the host stress response to the process of net cleaning and could be indicative of increased mortalities post-cleaning.

Introduction: Net biofouling has a significant impact for the global salmon industry in the seawater grow-out stage in terms of its management. Current mitigation strategies occur primarily through the regular removal of biofouling using in situ cleaning. While in situ net cleaning is effective there is uncertainty as to whether the equipment or dispersed material has an impact upon the fish in the cages. Through direct contact with the environment, the significant surface area of the gill including its microbiome is directly exposed to the acute environmental changes generated by net cleaning. This study aimed to provide a detailed understanding of the impact of in situ net cleaning on Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) gill health.Methods: Three field trials were conducted on commercial fish farms in western Norway. Fouling organisms on net pens and flushed particles during in situ cleaning were identified and screened for major fish pathogens. Hydrographic profile measurements were performed to measure the impact on water quality. Gill samples were examined for histopathological changes, immune gene expression, and the prevalence of major pathogens. 16S rRNA amplicon sequencing was employed to explore the impact of net cleaning on gill microbiome.Results and discussion: Data obtained from these trials identified a diversity of fouling species including hydroids, algae, skeleton shrimps, and filter feeders on net pens, a direct impact on measured water quality indicators, a moderate change in gill inflammatory and antigen presentation activity at the level of mRNA, and a large significant change in gill microbiome. Observed changes in gill microbial community involved a decrease in bacterial richness coupled to an increase in identified bacterial genera related to negative health consequences. Parallel analyses for pathogens load in biofouling organisms and flushed particles highlighted the presence of several fish bacteria and parasites. However, minor changes were detected in salmon gill pathogen diversity and loading. Our results suggest that biofouling organisms may act as transient reservoirs for some fish pathogens but not viruses and that gill microbial dysbiosis could be related to the host stress response during and post net cleaning.