# Fish Hatchery Biosecurity and Disease Prevention ## Key Takeaways - Effective fish hatchery biosecurity hinges on three core principles: pathogen exclusion (preventing entry via water, eggs, feed, personnel), pathogen containment (limiting spread within the facility through zoning and physical barriers), and pathogen reduction (lowering environmental loads via sanitation and water treatment). - Critical control points include egg disinfection immediately post-fertilization using agents like iodophors or hydrogen peroxide to mitigate vertical transmission, and rigorous quarantine protocols for new or returning fish, typically lasting 30-60 days with daily health monitoring and potential diagnostic sampling. - Routine health monitoring, encompassing daily observation of feeding response and behavior, precise mortality recording, and periodic diagnostic sampling, is essential for early disease detection and trend analysis, allowing for timely intervention before widespread outbreaks occur. - Facility design, including clear zoning into "clean" and "dirty" areas with unidirectional traffic flow, coupled with stringent personnel hygiene (handwashing, dedicated footwear) and equipment sanitation protocols, forms the physical and operational backbone of disease prevention. - Biosecurity programs must be supported by comprehensive record-keeping for all critical procedures (disinfection, quarantine, health monitoring, water quality) to enable protocol evaluation, troubleshooting, and informed decision-making, with clear criteria for escalating issues to veterinary professionals. --- ## At a Glance Fish hatchery biosecurity encompasses the management practices, facility design, and operational protocols that prevent the introduction and spread of pathogens within hatchery systems. Effective biosecurity programs protect egg survival, fry health, and broodstock performance while reducing the need for therapeutic interventions. The table below summarizes core biosecurity components and their primary functions. | Biosecurity Component | Primary Function | Typical Application Point | |---|---|---| | Egg disinfection | Reduce vertical pathogen transmission from broodstock to offspring | Immediately after fertilization and before incubation | | Quarantine protocols | Isolate new or returning fish until health status is confirmed | Separate tanks or facility zones with dedicated equipment | | Health monitoring | Detect disease signs early and track mortality patterns | Daily observation, record keeping, and periodic diagnostic sampling | | Facility sanitation | Eliminate pathogens from surfaces, water, and equipment | Between production cycles and after disease events | | Water treatment | Remove or inactivate waterborne pathogens | At intake, recirculation, and effluent points | | Personnel hygiene | Prevent pathogen transfer via staff, visitors, and tools | Entry points, between tanks, and after handling sick fish | ## Scope and Reader Context This article provides hatchery biosecurity officers with practical guidance on implementing disease prevention measures specific to fish hatcheries. The content covers egg disinfection, quarantine procedures, health monitoring protocols, facility sanitation, and record keeping. The focus is on management decisions that hatchery staff can apply directly, with attention to limitations and criteria for escalating problems to veterinary or diagnostic professionals. The information draws on published evidence from FAO, USDA, and peer-reviewed journals, but does not replace site-specific veterinary advice or regulatory requirements. ## Core Principles of Hatchery Biosecurity Biosecurity in fish hatcheries rests on three foundational principles: pathogen exclusion, pathogen containment, and pathogen reduction. Exclusion prevents pathogens from entering the hatchery through incoming water, eggs, broodstock, feed, equipment, or personnel. Containment limits the spread of pathogens within the hatchery if an introduction occurs. Reduction lowers pathogen loads in the hatchery environment through sanitation, water treatment, and disinfection. The FAO Fisheries and Aquaculture Department provides resources on cultured species and production systems that emphasize the importance of biosecurity for sustainable aquaculture (www.fao.org/fishery/en/culturedspecies). The USDA Agricultural Research Service supports research on aquaculture health management, including pathogen detection and control strategies (www.ars.usda.gov/animal-production-and-protection/aquaculture). These sources underscore that biosecurity is an integrated system of practices tailored to the hatchery's species, water source, and production scale. A review of biosecurity protocols and fish health management in Kenyan fish hatcheries found that hatcheries with documented biosecurity plans produced higher quality fish seed and experienced fewer disease outbreaks (Biosecurity protocols and fish health management in Kenyan fish hatcheries: a key to sustainable production of quality fish seed, Marine and Fishery Sciences, 2025, doi.org/10.47193/mafis.3812025010102). This finding aligns with observations from other regions where biosecurity capacity varies widely. An international evaluation of biosecurity management capacity in the seaweed aquaculture industry noted similar gaps in biosecurity implementation across different production sectors (An international evaluation of biosecurity management capacity in the seaweed aquaculture industry, Journal of Environmental Management, 2022, pubmed.ncbi.nlm.nih.gov/34923419). For fish hatcheries, the lesson is clear: written biosecurity plans must be translated into daily practice. ## Facility Design and Zoning Hatchery layout directly influences biosecurity effectiveness. Zoning separates areas of different health risk levels and establishes physical barriers that prevent pathogen movement. ### Clean and Dirty Zones A well-designed hatchery divides the facility into clean zones (low pathogen risk) and dirty zones (higher pathogen risk). Clean zones include egg incubation rooms, larval rearing areas, and broodstock holding tanks with known health status. Dirty zones include receiving areas for new fish, quarantine units, and waste handling areas. The flow of water, air, equipment, and personnel should move from clean to dirty zones, never the reverse. ### Physical Barriers Physical barriers between zones include separate entrances, footbaths, handwashing stations, and dedicated equipment for each zone. Walls or partitions prevent aerosol and splash transmission. Drainage systems should be designed so that water from dirty zones does not flow toward clean zones. The USDA National Agricultural Library provides resources on animal health and welfare that include facility design considerations for disease prevention (www.nal.usda.gov/animal-health-and-welfare). ### Traffic Flow Personnel movement should follow a one-way path from clean to dirty areas whenever possible. Staff working in quarantine or disease treatment areas should not enter egg incubation or larval rearing rooms on the same day without showering and changing clothing. Visitor access must be restricted and logged. Equipment such as nets, buckets, and hoses should be color-coded by zone and never shared between zones without disinfection. ## Egg Disinfection Egg disinfection is a critical control point for preventing vertical transmission of pathogens from broodstock to offspring. Many fish pathogens, including viruses and bacteria, can adhere to egg surfaces or be carried in ovarian fluid. ### Disinfection Timing and Methods Egg disinfection should occur as soon as possible after fertilization and before eggs are placed in incubation systems. Common disinfectants include iodophors (e.g., povidone-iodine), hydrogen peroxide, and formalin, each with specific concentration and exposure time requirements. The choice of disinfectant depends on the target pathogen, egg species, and egg stage. Overdosing or prolonged exposure can reduce hatch rates, while underdosing may fail to eliminate pathogens. ### Limitations of Egg Disinfection Egg disinfection does not eliminate pathogens that have already penetrated the egg interior. Some viruses, such as those in the family Rhabdoviridae, can be transmitted internally and may not be removed by surface disinfection (ICTV Virus Taxonomy Profile: Rhabdoviridae 2022, Journal of General Virology, 2022, pubmed.ncbi.nlm.nih.gov/35723908). For this reason, egg disinfection must be combined with broodstock health screening and quarantine. ### Record Keeping for Egg Disinfection Each egg batch should be documented with the following information: broodstock source and health history, date and time of fertilization, disinfectant product and concentration, exposure duration, water temperature and pH during treatment, and hatch rate. This record allows hatchery staff to evaluate disinfection effectiveness and adjust protocols if hatch rates decline or disease appears. ## Quarantine Procedures Quarantine isolates new or returning fish until their health status is confirmed. This prevents the introduction of pathogens that may be carried by apparently healthy fish. ### Quarantine Facility Requirements The quarantine area must be physically separate from the main hatchery, with its own water supply, drainage, and equipment. Ideally, quarantine tanks are located in a different building or room. Water from quarantine should not recirculate into the main system unless treated to inactivate pathogens. Dedicated nets, buckets, and other tools must remain in quarantine and not be used elsewhere. ### Quarantine Duration and Monitoring The minimum quarantine period depends on the species, source, and known disease risks. A typical quarantine lasts 30 to 60 days, during which fish are observed daily for signs of disease. Mortality should be recorded and dead fish removed promptly. Diagnostic testing may be performed at the beginning and end of quarantine to confirm absence of specific pathogens. The FAO Animal Production and Health division provides guidance on animal health management that includes quarantine principles applicable to aquaculture (www.fao.org/animal-production/en). ### Quarantine Records Maintain a quarantine log for each group of fish. Record the following: source and date of arrival, number of fish, species and size, water quality parameters (temperature, dissolved oxygen, pH, ammonia, nitrite), daily observations of behavior and feeding, any mortalities with dates and suspected causes, treatments administered, and diagnostic test results. This log becomes part of the hatchery's health history and supports decisions about releasing fish into the main production system. ## Health Monitoring Protocols Health monitoring is the systematic observation and recording of fish health indicators to detect disease early and track trends over time. ### Daily Observations Hatchery staff should inspect fish at least once daily, preferably at the same time each day. Observations include feeding response, swimming behavior, body condition, fin and skin appearance, and the presence of external lesions, parasites, or abnormal coloration. Any deviation from normal should be noted and investigated. ### Mortality Recording All mortalities must be collected, counted, and recorded daily. Mortality rates are calculated as a percentage of the population and tracked over time. A sudden increase in mortality, especially if concentrated in a single tank or age group, warrants immediate investigation. Dead fish should be removed promptly to prevent disease transmission and water quality deterioration. ### Diagnostic Sampling Periodic diagnostic sampling involves collecting fish for laboratory analysis. Samples may be taken from apparently healthy fish to screen for subclinical infections, or from sick or dead fish to identify the cause of disease. Sample size and selection should follow veterinary guidance. The USDA Agricultural Research Service supports research on diagnostic methods for aquaculture pathogens (www.ars.usda.gov/animal-production-and-protection/aquaculture). ### Health Monitoring Records Maintain a health monitoring log for each tank or production unit. Record daily observations, mortality counts, water quality parameters, treatments, and any diagnostic results. Review these records weekly to identify trends. A pattern of increasing mortality or recurring clinical signs in a particular tank may indicate an underlying problem that requires veterinary consultation. ## Water Quality Management Water quality directly affects fish health and disease resistance. Poor water quality stresses fish and makes them more susceptible to pathogens. ### Key Water Quality Parameters Dissolved oxygen, temperature, pH, ammonia, nitrite, and nitrate are the primary parameters to monitor in hatchery systems. Each species has an optimal range for these parameters. Sudden changes or prolonged deviations from optimal ranges can trigger disease outbreaks. For example, low dissolved oxygen increases susceptibility to bacterial infections, while high ammonia damages gill tissue and impairs immune function. ### Water Treatment Water treatment methods include mechanical filtration (removing solids), biological filtration (converting ammonia to nitrate), ultraviolet (UV) sterilization, ozonation, and chemical disinfection. The choice of treatment depends on water source quality, system type (flow-through or recirculating), and target pathogens. UV and ozone are effective against many bacteria and viruses but require proper sizing and maintenance. ### Water Quality Records Record water quality parameters at least daily for each tank or system. Include the date, time, tank identification, parameter values, and any corrective actions taken. Review records to identify trends and prevent problems before they affect fish health. If water quality parameters fall outside acceptable ranges and cannot be corrected with routine adjustments, consult a water quality specialist or veterinarian. ## Sanitation and Disinfection Sanitation removes organic matter and reduces pathogen loads on surfaces and equipment. Disinfection kills remaining pathogens after cleaning. ### Cleaning Protocols All tanks, pipes, filters, and equipment should be cleaned between production cycles. Cleaning involves removing organic debris, scrubbing surfaces with detergent, and rinsing thoroughly. Organic matter can protect pathogens from disinfectants, so cleaning must precede disinfection. ### Disinfection Protocols After cleaning, apply an appropriate disinfectant to surfaces and equipment. Common disinfectants for hatchery use include chlorine compounds, iodophors, hydrogen peroxide, and peracetic acid. Each disinfectant has a recommended concentration, contact time, and safety precautions. Rinse disinfected surfaces with clean water before reintroducing fish. ### Disinfection Records Document each sanitation and disinfection event. Record the date, area or equipment treated, cleaning method, disinfectant product and concentration, contact time, and the person performing the work. This record supports quality assurance and helps identify if disease outbreaks are linked to incomplete sanitation. ## Personnel Hygiene and Training Personnel can transfer pathogens between tanks, rooms, and facilities on hands, clothing, and footwear. ### Hand Hygiene Handwashing with soap and water or using alcohol-based hand sanitizer should be required before entering fish holding areas and after handling fish, equipment, or waste. Handwashing stations should be located at all entry points and near tanks. ### Footwear and Clothing Dedicated footwear or disposable boot covers should be worn in fish holding areas. Footbaths with disinfectant solution can be placed at zone boundaries, but they must be maintained with fresh disinfectant at the correct concentration. Clothing should be clean and dedicated to the hatchery. Some facilities require staff to shower and change into facility-provided clothing before entering clean zones. ### Training All staff must receive training on biosecurity protocols, including the reasons for each practice and the consequences of noncompliance. Training should be documented and repeated annually or when protocols change. New staff should be supervised until they demonstrate consistent compliance. ## Common Failure Patterns Hatchery biosecurity programs often fail due to specific recurring problems. Recognizing these patterns helps hatchery staff correct weaknesses before disease outbreaks occur. ### Inconsistent Protocol Application The most common failure is inconsistent application of biosecurity protocols. Staff may follow procedures correctly most of the time but skip steps when busy or when no disease is apparent. This inconsistency creates gaps that pathogens can exploit. Regular audits and refresher training reduce this risk. ### Inadequate Quarantine Quarantine is often shortened or bypassed when production targets are urgent. New fish may be moved into the main hatchery before quarantine is complete, introducing pathogens. Strict adherence to quarantine duration and monitoring is essential, regardless of production pressure. ### Poor Record Keeping Without accurate records, hatchery staff cannot identify trends, evaluate protocol effectiveness, or demonstrate compliance with regulations. Records that are incomplete, illegible, or not reviewed are of little value. Assign responsibility for record keeping and review records regularly. ### Cross-Contamination via Equipment Shared equipment is a common route of pathogen transfer. Nets, buckets, and hoses used in quarantine or disease treatment areas may be used elsewhere without disinfection. Color-coding equipment by zone and enforcing strict separation prevents this failure. ### Water Quality Neglect Water quality problems often precede disease outbreaks. Hatcheries that monitor water quality infrequently or fail to act on out-of-range readings may experience disease even when other biosecurity measures are in place. Daily monitoring and prompt corrective action are nonnegotiable. ## Limitations and Professional Escalation Hatchery biosecurity has limitations that must be recognized. No protocol can eliminate all disease risk. Some pathogens are highly resistant to disinfection, and some fish may carry infections without showing signs. Biosecurity reduces risk but does not guarantee disease freedom. ### When to Escalate Escalate to a veterinarian or aquatic animal health specialist under the following circumstances: - Mortality exceeds baseline levels for more than 48 hours and the cause is not obvious. - Clinical signs suggest a notifiable or reportable disease. - Diagnostic tests return positive results for a pathogen of concern. - Water quality problems cannot be corrected with routine adjustments. - A disease outbreak spreads despite implementation of biosecurity protocols. ### Regulatory Context Some fish diseases are reportable to national or international authorities. Hatchery staff should know which diseases are notifiable in their jurisdiction and have a plan for reporting. The FAO and World Organisation for Animal Health (WOAH) provide guidance on disease reporting and control. The USDA National Agricultural Library offers resources on animal health regulations (www.nal.usda.gov/animal-health-and-welfare). ### Welfare Considerations Disease prevention through biosecurity is a core component of fish welfare. Sick fish experience stress, pain, and reduced quality of life. Preventing disease is more humane than treating it. Hatchery staff have a responsibility to maintain conditions that minimize disease risk and to seek veterinary care when fish are sick. ## Practical Decision Framework for Biosecurity Protocol Selection Hatchery managers face a range of biosecurity options and must select protocols that match their specific production context, species, water source, and disease history. A structured decision framework helps staff evaluate trade-offs between efficacy, cost, operational feasibility, and fish welfare. This section provides a practical framework for selecting and adjusting biosecurity protocols based on hatchery-specific risk factors. ### Risk Assessment Matrix for Protocol Selection Begin by assessing your hatchery's risk profile across four domains: pathogen introduction risk, pathogen transmission risk, production vulnerability, and treatment capacity. Score each domain as low, medium, or high based on observable conditions. Pathogen introduction risk depends on the source and frequency of incoming fish and eggs. Hatcheries that obtain broodstock or eggs from certified disease-free sources with documented health histories have lower introduction risk than those sourcing from wild populations or multiple suppliers with unknown health status. The FAO Fisheries and Aquaculture Department provides resources on cultured species that include guidance on sourcing disease-free stock (www.fao.org/fishery/en/culturedspecies). Hatcheries that import fish from other regions or countries face higher introduction risk due to potential exposure to pathogens not present locally. Pathogen transmission risk reflects the hatchery's facility design and operational practices. Single-pass flow-through systems with separate water supplies for each tank have lower transmission risk than recirculating systems where water is shared. High stocking densities, shared equipment, and inadequate zoning increase transmission risk. A review of aquaculture production and health management practices in Kenya found that hatcheries with higher stocking densities and shared water systems experienced more frequent disease outbreaks (A review of aquaculture production and health management practices of farmed fish in Kenya, International Journal of [Veterinary Science](/blog/news/veterinary-science) and Medicine, 2018, pubmed.ncbi.nlm.nih.gov/30564588). Production vulnerability considers the species and life stage being raised. Larval and fry stages are more vulnerable to disease than older fish. Species with known susceptibility to specific pathogens require targeted protocols. For example, tilapia hatcheries in Brazil were assessed for biosecurity practices, and the study highlighted that fry production stages require the most stringent protocols due to high vulnerability (Aquaculture biosecurity in Brazil: Assessment of tilapia fry hatcheries in the Federal District, Boletim do Instituto De Pesca, 2026, doi.org/10.20950/1678-2305/bip.2026.52.e1006). Treatment capacity refers to the hatchery's ability to respond to disease events. Hatcheries with access to veterinary diagnostic services, treatment medications, and isolation facilities have higher treatment capacity than those without these resources. Hatcheries with limited treatment capacity should prioritize prevention through stricter biosecurity protocols. ### Protocol Selection Matrix Use the risk assessment scores to select appropriate protocols from the table below. For each risk domain, choose the protocol tier that matches your hatchery's score. | Risk Domain | Low Risk | Medium Risk | High Risk | |---|---|---|---| | Pathogen introduction | Standard quarantine (30 days), visual inspection only | Extended quarantine (45-60 days), diagnostic testing at entry and exit | Maximum quarantine (60+ days), testing for specific pathogens, separate facility | | Pathogen transmission | Basic zoning, shared equipment with disinfection between uses | Enhanced zoning with physical barriers, dedicated equipment per zone | Complete separation of zones, one-way traffic flow, dedicated staff per zone | | Production vulnerability | Standard disinfection protocols, routine monitoring | Increased disinfection frequency, daily health scoring, reduced stocking density | Maximum disinfection protocols, twice-daily monitoring, lowest stocking density | | Treatment capacity | Basic first aid treatments, call veterinarian when mortality exceeds 2% per day | Stock common treatments, have veterinary relationship established, call at 1% daily mortality | Pre-arranged veterinary support, diagnostic testing on site, call at any mortality increase | ### Implementation Steps for Protocol Selection Follow these steps to implement the decision framework in your hatchery. Step 1: Conduct a baseline risk assessment for each production unit or tank system. Use the four risk domains and score each as low, medium, or high. Document the scores and the evidence supporting each score. Step 2: Select protocols from the matrix that match your risk scores. For example, a hatchery with high introduction risk and high production vulnerability should implement maximum quarantine and maximum disinfection protocols. Step 3: Document the selected protocols in a written biosecurity plan. Include the specific procedures, responsible staff, and frequency of each protocol. The plan should be reviewed and updated at least annually or when risk factors change. Step 4: Train all staff on the selected protocols and the rationale behind them. Staff should understand why different protocols apply to different tanks or production stages. Step 5: Monitor protocol effectiveness using the record system described below. Adjust protocols if disease events occur or if risk scores change. ### Record System for Protocol Effectiveness Maintain a biosecurity protocol log for each production unit. Record the following information for each protocol application: - Date and time of protocol application - Protocol name and specific procedure used - Tank or unit identification - Staff member performing the protocol - Any deviations from the standard procedure and the reason - Observations of fish health before and after protocol application - Any adverse effects on fish (e.g., reduced feeding, increased mortality) Review these records weekly to identify patterns. If a protocol is consistently associated with adverse effects or if disease events occur despite protocol application, investigate the cause and adjust the protocol or risk assessment. ### Troubleshooting Method for Protocol Failures When a disease event occurs despite biosecurity protocols, use the following troubleshooting method to identify the failure point. Step 1: Review records for the affected tank or unit for the 14 days before the disease event. Look for deviations from standard protocols, missed protocol applications, or changes in water quality parameters. Step 2: Interview staff who worked with the affected fish. Ask about any unusual observations, equipment sharing, or visitor access that may have introduced pathogens. Step 3: Inspect the physical facility for breaches in biosecurity barriers. Check for cracks in walls, gaps in doors, shared drainage lines, or equipment that may have been moved between zones without disinfection. Step 4: Review water quality records for the affected tank and adjacent tanks. Look for trends in temperature, dissolved oxygen, pH, ammonia, or nitrite that may have stressed fish and increased susceptibility. Step 5: If the failure point is identified, correct it immediately and document the corrective action. If the failure point is not identified, escalate to a veterinarian or aquatic animal health specialist for diagnostic investigation. ### Comparison of Disinfection Protocols for Different Risk Levels The table below compares disinfection protocols for egg disinfection and facility sanitation across risk levels. | Protocol Element | Low Risk | Medium Risk | High Risk | |---|---|---|---| | Egg disinfection frequency | Once after fertilization | Once after fertilization plus second treatment before hatching | Three treatments: after fertilization, at eye-up stage, before hatching | | Egg disinfectant concentration | Standard label rate | 1.5 times standard rate (if species tolerance allows) | Maximum label rate with species tolerance testing | | Facility disinfection between cycles | Single cleaning and disinfection | Double cleaning and disinfection with different disinfectant classes | Triple cleaning and disinfection with disinfectant rotation | | Footbath maintenance | Weekly replacement | Daily replacement | Replacement after each use or between zones | ### Limitations of the Decision Framework This framework provides guidance but has limitations. Risk scores are based on observable conditions and staff judgment, which may vary between hatcheries and over time. The protocol tiers are general recommendations and may need adjustment for specific species, pathogens, or regulatory requirements. The framework does not replace veterinary advice or diagnostic testing. If disease events occur despite following the framework, consult a veterinarian or aquatic animal health specialist. A study on biosecurity in aquaculture noted that effective biosecurity requires continuous adaptation to changing conditions and emerging pathogens (Biosecurity in Aquaculture, Antimicrobial Resistance in Aquaculture and Aquatic Environments, 2025, doi.org/10.1007/978-981-97-7320-6_14). Hatcheries should treat this framework as a starting point and refine it based on their own experience and disease history. ## Frequently Asked Questions ### What is the most important biosecurity measure for a fish hatchery? The most important measure is preventing pathogen introduction through incoming fish and eggs. This requires effective quarantine of all new stock and disinfection of eggs before they enter the hatchery. Without these measures, other biosecurity practices cannot compensate for the continuous introduction of pathogens. ### How long should fish be quarantined in a hatchery? Quarantine duration depends on the species, source, and disease risks. A minimum of 30 days is common, but 60 days is recommended for high-risk sources or when testing for slow-developing diseases. The quarantine period should be long enough to allow clinical signs to appear and for diagnostic testing to be completed. ### Can egg disinfection eliminate all fish pathogens? No. Egg disinfection reduces surface pathogens but does not eliminate pathogens that have penetrated the egg interior. Some viruses, including rhabdoviruses, can be transmitted internally. Egg disinfection must be combined with broodstock health screening and quarantine to be effective. ### What records should a hatchery keep for biosecurity? Essential records include egg disinfection logs, quarantine logs, health monitoring logs, mortality records, water quality records, sanitation and disinfection records, and personnel training records. These records support disease investigation, protocol evaluation, and regulatory compliance. ### How often should hatchery water quality be tested? Water quality should be tested at least daily for dissolved oxygen, temperature, and pH. Ammonia and nitrite should be tested at least weekly in recirculating systems and more frequently during system startup or after stocking. Additional parameters may be needed depending on water source and species. ### What disinfectants are safe for fish eggs? Iodophors, hydrogen peroxide, and formalin are commonly used for fish egg disinfection. Each has specific concentration and exposure time requirements that vary by species and egg stage. Always follow manufacturer instructions and consult species-specific guidelines to avoid reducing hatch rates. ### How can hatchery staff prevent cross-contamination between tanks? Use dedicated equipment for each tank or zone, color-code equipment by zone, and enforce strict separation. Disinfect equipment between uses if it must be shared. Follow a one-way traffic flow from clean to dirty areas. Handwashing and footbaths at zone boundaries reduce personnel-mediated transfer. ### When should a veterinarian be called for hatchery disease problems? Call a veterinarian when mortality exceeds baseline levels for more than 48 hours without an obvious cause, when clinical signs suggest a notifiable disease, when diagnostic tests identify a pathogen of concern, or when disease spreads despite biosecurity measures. Early veterinary involvement improves outcomes and reduces losses. ## Related Farming Guides - [Genomic Health](/blog/guides/genome-browsers-for-researchers-a-guide-to-inspecting-genomic-evidence) - [Aquaponics Fish Health And System Management](/knowledge/animal-farming/aquaculture/aquaponics-fish-health-and-system-management) - [Fish Farming Water Feed Stocking Biosecurity Welfare And Harvest Decisions](/knowledge/animal-farming/aquaculture/fish-farming-water-feed-stocking-biosecurity-welfare-and-harvest-decisions) - [Farm Health Intelligence Observation Records Biosecurity Diagnostics And Veterinary Escalation](/knowledge/animal-farming/farm-management/farm-health-intelligence-observation-records-biosecurity-diagnostics-and-veterinary-escalation) - [Feeding Farmed Fish Efficiently](/knowledge/animal-farming/aquaculture/feeding-farmed-fish-efficiently) ## Related Clinical & Scientific Guides * [Pond Sediment Management and Dredging Options](/knowledge/animal-farming/aquaculture/pond-sediment-management-dredging-options) * [Indoor Aquaculture Facilities: Lighting and Insulation](/knowledge/animal-farming/aquaculture/indoor-aquaculture-facilities-lighting-insulation) * [Greenhouse Aquaculture: Extending Growing Seasons](/knowledge/animal-farming/aquaculture/greenhouse-aquaculture-extending-growing-seasons) ## References and Further Reading - [www.fao.org](https://www.fao.org/fishery/en/culturedspecies) - [www.ars.usda.gov](https://www.ars.usda.gov/animal-production-and-protection/aquaculture) - [FAO Animal Production and Health](https://www.fao.org/animal-production/en). Food and Agriculture Organization of the United Nations. - [Animal Health and Welfare](https://www.nal.usda.gov/animal-health-and-welfare). USDA National Agricultural Library. - [Vibriosis in Fish: A Review on Disease Development and Prevention.](https://pubmed.ncbi.nlm.nih.gov/30246889). Journal of aquatic animal health, 2019. - [Biosecurity and the ornamental fish trade: A stakeholder perspective in England.](https://pubmed.ncbi.nlm.nih.gov/34699063). Journal of fish biology, 2022. - [A review of aquaculture production and health management practices of farmed fish in Kenya.](https://pubmed.ncbi.nlm.nih.gov/30564588). International journal of [veterinary science](/blog/news/veterinary-science) and medicine, 2018. - [Vulnerabilities in aquatic animal production.](https://pubmed.ncbi.nlm.nih.gov/31866684). Revue scientifique et technique (International Office of Epizootics), 2019. - [ICTV Virus Taxonomy Profile: Rhabdoviridae 2022.](https://pubmed.ncbi.nlm.nih.gov/35723908). The Journal of general virology, 2022. - [An international evaluation of biosecurity management capacity in the seaweed aquaculture industry.](https://pubmed.ncbi.nlm.nih.gov/34923419). Journal of environmental management, 2022. - [Biosecurity protocols and fish health management in Kenyan fish hatcheries: a key to sustainable production of quality fish seed](https://doi.org/10.47193/mafis.3812025010102). Marine and Fishery Sciences, 2025. - [Aquaculture development and biosecurity challenges in Uganda: toward resilient fish health management](https://doi.org/10.47853/FAS.2026.e18). Fisheries and Aquatic Sciences, 2026. - [Biosecurity in Aquaculture](https://doi.org/10.1007/978-981-97-7320-6_14). Antimicrobial Resistance in Aquaculture and Aquatic Environments, 2025. - [Sustainable fish production in Egypt: towards strategic management for capture-based aquaculture](https://doi.org/10.1007/s10499-024-01470-y). Aquaculture International, 2024. - [Aquaculture biosecurity in Brazil: Assessment of tilapia fry hatcheries in the Federal District](https://doi.org/10.20950/1678-2305/bip.2026.52.e1006). Boletim do Instituto De Pesca, 2026. > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.