# Cod [Fish Farming](/knowledge/animal-farming/aquaculture/fish-farming-water-feed-stocking-biosecurity-welfare-and-harvest-decisions): Hatchery, Grow-Out, and Harvest Management ## Key Takeaways - **Hatchery phase critical for juvenile quality:** Success hinges on stable water quality (8-12°C, >7 mg/L DO, <0.1 mg/L ammonia), precise live feed management (rotifers, Artemia), and successful weaning to dry diets by 45-50 days to mitigate nutritional deficiencies and cannibalism. - **Grow-out demands precise environmental and nutritional control:** Optimal growth (3-5 kg in 18-24 months) requires stocking densities of 10-20 kg/m³, high-protein diets (45-55%), and vigilant water quality monitoring, particularly dissolved oxygen (>5 mg/L) to prevent bacterial infections and environmental stress. - **Disease prevention is paramount:** Biosecurity measures, vaccination against common bacterial pathogens (e.g., Vibrio, Furunculosis), and regular health checks are crucial to combat significant threats like Viral Haemorrhagic Septicaemia (VHS). - **Harvesting requires welfare focus and rapid processing:** Minimizing stress during crowding (max 2 hours) and ensuring rapid chilling (0-2°C within 30 minutes of harvest) are essential to prevent stress-induced mortality and maintain flesh quality. - **Feed management is a primary economic driver:** Optimizing feed conversion ratio (target 1.0-1.3) through appropriate particle size, feeding frequency (2-4 times daily for smaller fish), and seasonal temperature adjustments (0.5-1.8% body weight daily) is critical for profitability. - **Comprehensive record-keeping is non-negotiable:** Detailed logs of broodstock, hatchery, grow-out, and harvest parameters, alongside key performance indicators like survival rates and FCR, are vital for management decisions and regulatory compliance. --- ## At a Glance Cod [fish farming](/knowledge/animal-farming/aquaculture/fish-farming-water-feed-stocking-biosecurity-welfare-and-harvest-decisions) involves three distinct production phases: hatchery, grow-out, and harvest. Each phase requires specific management decisions regarding water quality, feeding, disease control, and handling. The table below summarizes key operational parameters for each phase. | Phase | Duration | Primary Management Focus | Key Risk Factors | |-------|----------|------------------------|------------------| | Hatchery | 60-90 days from egg to juvenile | Water quality stability, live feed production, weaning to dry feed | Viral haemorrhagic septicaemia (VHS), nutritional deficiencies, cannibalism | | Grow-out | 18-24 months to market size (3-5 kg) | [Feed conversion ratio](/knowledge/animal-farming/poultry/feed-conversion-ratio-measuring-improving-poultry-efficiency), stocking density, disease surveillance | Bacterial infections, sea lice, environmental stress | | Harvest | 1-2 days per cage | Welfare during crowding, rapid chilling, quality grading | Stress-induced mortality, flesh quality degradation, [food safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) compliance | ## Hatchery Management ### Broodstock Selection and Conditioning Broodstock selection directly affects egg quality, larval survival, and juvenile performance. Atlantic cod broodstock should be sourced from genetically diverse populations to maintain heterozygosity and reduce inbreeding depression. Large-scale sequence analyses of Atlantic cod have provided tools for genetic management in breeding programs [10]. Farmers should maintain broodstock at low stocking densities (5-10 kg/m³) with controlled photoperiod and temperature cycles to synchronize spawning. Conditioning begins 8-12 weeks before expected spawning. Temperature is gradually reduced to 4-6°C, then increased to 6-8°C to trigger final oocyte maturation. Photoperiod manipulation using 12-16 hours of light per day can extend the spawning season. Broodstock nutrition requires high-quality marine proteins and lipids, particularly long-chain polyunsaturated fatty acids (EPA and DHA), which are critical for egg and larval development. ### Egg Incubation and Hatching Cod eggs are pelagic and require gentle upwelling incubation systems. Incubation temperature should be maintained at 5-7°C with salinity at 32-35 ppt. Eggs hatch after 12-18 days depending on temperature. Dead eggs and debris must be removed daily to prevent fungal and bacterial proliferation. Hatching success is recorded as a percentage of viable eggs. Farmers should track egg diameter, oil globule size, and fertilization rate. Poor hatching success often indicates suboptimal broodstock nutrition or water quality issues. Professional escalation is warranted if hatching rates fall below 50% for two consecutive spawns. ### Larval Rearing Larval rearing is the most technically demanding phase of cod farming. Larvae are altricial at hatch, with undeveloped digestive systems and limited swimming ability. First feeding begins 3-5 days post-hatch when the mouth opens and yolk sac is partially absorbed. Live feed is essential during the first 30-40 days. Rotifers enriched with algae and commercial emulsions provide initial nutrition. Artemia nauplii are introduced from day 20-25. Weaning to formulated microdiets begins around day 30-35 and is completed by day 45-50. Water quality parameters during larval rearing: - Temperature: 8-12°C (gradually increased from hatch) - Salinity: 32-35 ppt - Dissolved oxygen: >7 mg/L - Ammonia: <0.1 mg/L - Light intensity: 100-500 lux during feeding Cannibalism is a common failure pattern during larval rearing, particularly when size variation exceeds 30% of body length. Grading every 7-10 days reduces losses. Farmers should record daily mortality, feed intake, and larval length measurements. ### Juvenile Production Juveniles are transferred to nursery tanks or sea cages at 1-5 grams. Acclimation to ambient seawater temperature and salinity must be gradual over 7-14 days. Vaccination against common bacterial pathogens is typically performed at this stage. Vaccines for fish in aquaculture have been developed for several bacterial diseases affecting cod, including vibriosis and furunculosis [5]. The status and future perspectives of vaccines for industrialised fin-fish farming indicate that vaccination protocols should be tailored to local pathogen prevalence [7]. Nursery phase duration is 2-4 months until fish reach 50-100 grams. Stocking density in tanks should not exceed 20-30 kg/m³. Feeding rates start at 5-8% body weight per day and decrease to 2-3% as fish grow. ## Grow-Out Management ### Site Selection and Cage Systems Grow-out sites require adequate water exchange, depth (>30 meters), and protection from severe weather. Bottom type should be sand or mud to minimize net abrasion. Current speeds of 0.5-1.5 m/s are optimal for waste dispersion. Cage types used in cod farming include: - Circular plastic cages (20-50 m diameter) - Steel square cages (15-25 m per side) - Submersible cages for winter storm protection Stocking density in sea cages should be maintained at 10-20 kg/m³. Higher densities increase stress and disease susceptibility. The viability of capture-based aquaculture for Atlantic cod in Norway has been evaluated, showing that wild-caught juveniles can supplement hatchery production but require careful management [11]. ### Feeding and Nutrition Cod are carnivorous and require high-protein diets (45-55% crude protein) with moderate lipid levels (15-25%). Feed ingredients should include fishmeal, fish oil, and plant-based protein sources where economically feasible. Forage fish for cod and people highlights the ecological and economic trade-offs in using wild fish for aquaculture feed [6]. Feeding management: - Feed particle size increases with fish size (2-12 mm) - Feeding frequency: 2-4 times daily for fish <1 kg, 1-2 times for larger fish - Feed conversion ratio target: 1.0-1.3 kg feed per kg gain - Automatic feeders with demand sensors reduce waste Farmers should record daily feed input, estimated biomass, and feed conversion ratio weekly. Uneaten feed accumulation beneath cages indicates overfeeding and should be corrected immediately. ### Water Quality Monitoring Dissolved oxygen is the most critical water quality parameter in grow-out cages. Levels below 5 mg/L cause reduced feed intake and growth. Levels below 3 mg/L cause mortality. Oxygen monitoring should be continuous at multiple depths within the cage. Other parameters to monitor: - Temperature: 4-15°C optimal range - Salinity: 30-35 ppt - Ammonia: <0.5 mg/L - pH: 7.5-8.5 - Current speed: measured weekly Temperature stratification and algal blooms can cause sudden oxygen depletion. Farmers should have emergency aeration systems available and activate them when oxygen drops below 5 mg/L. ### Disease Prevention and Health Management Disease prevention relies on biosecurity, vaccination, and stress reduction. Viral haemorrhagic septicaemia virus in marine fish and its implications for fish farming has been reviewed, and VHS is a significant concern for cod aquaculture [8]. Clinical signs include lethargy, darkening, exophthalmia, and hemorrhages in skin and muscle. Health management protocols: - Quarantine new fish for 30 days before introduction - Restrict vessel and equipment movement between sites - Remove dead fish daily and dispose properly - Conduct monthly health checks with sample collection - Record all treatments and mortalities Professional escalation is required when: - Daily mortality exceeds 0.5% for three consecutive days - Clinical signs of notifiable diseases appear - Feed intake drops by more than 30% for one week ### Growth Monitoring and Grading Growth is monitored through monthly sampling of 50-100 fish per cage. Weight and length measurements are recorded and used to calculate specific growth rate and condition factor. Size grading every 2-3 months reduces competition and improves uniformity. Growth targets for Atlantic cod: - 0-6 months: 50-100 g - 6-12 months: 300-800 g - 12-18 months: 1.5-2.5 kg - 18-24 months: 3-5 kg Poor growth may indicate nutritional deficiencies, suboptimal temperature, or chronic disease. Farmers should investigate and correct underlying causes before growth depression becomes severe. ## Harvest Management ### Pre-Harvest Preparation Harvest planning begins 4-6 weeks before the target date. Fish are sampled to estimate biomass and size distribution. Feed is withdrawn 3-7 days before harvest to empty the gut and improve flesh quality. Withdrawal periods for any medications must be observed according to regulatory requirements. Crowding is performed 12-24 hours before harvest. Fish are concentrated using a crowding net or by reducing cage volume. Welfare during crowding is critical. Animal Welfare Issues in Capture-Based Aquaculture emphasize that stress during harvest affects flesh quality and fish welfare [9]. Crowding should be gradual and last no more than 2 hours. ### Harvest Methods Two primary harvest methods are used in cod farming: 1. **Live chilling**: Fish are pumped or netted from the cage into chilled seawater (0-2°C). Chilling reduces metabolic rate and stress before slaughter. Fish are then stunned and bled. 2. **Direct stunning**: Fish are stunned immediately after removal from water using percussive or electrical stunning. Bleeding is performed within 5 minutes of stunning. Both methods require rapid processing to maintain flesh quality. Time from harvest to chilling should not exceed 30 minutes. ### Quality Grading and Processing Harvested cod are graded by weight, appearance, and flesh quality. Grading criteria include: - Weight class: 1-2 kg, 2-3 kg, 3-4 kg, >4 kg - External appearance: scale loss, fin damage, skin lesions - Flesh quality: color, texture, gaping, blood spots Fish are packed in ice or refrigerated seawater for transport. Temperature should be maintained at 0-2°C from harvest to processing. Norway's cod farming industry has developed specific quality standards for farmed cod that differ from wild-caught standards [12]. ### [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Considerations Food safety in cod farming involves controlling hazards at every production stage. Key hazards include: - Biological: bacteria (Listeria, Vibrio), parasites (nematodes) - Chemical: heavy metals, pesticides, antibiotic residues - Physical: bone fragments, metal from equipment Farmers must maintain records of all inputs, treatments, and harvests to support traceability. The USDA National Agricultural Library provides resources on animal health and welfare that apply to aquaculture food safety [4]. ## Records and Measurements ### Essential Records Accurate records support management decisions and regulatory compliance. The following records should be maintained for each production cycle: - **Broodstock records**: Source, age, weight, spawning dates, egg production, fertilization rate - **Hatchery records**: Daily mortality, temperature, feeding rates, larval length, weaning success - **Grow-out records**: Stocking density, feed input, mortality, growth samples, water quality, treatments - **Harvest records**: Biomass harvested, size distribution, quality grades, transport conditions ### Key Performance Indicators | Indicator | Calculation | Target | |-----------|-------------|--------| | Survival rate (hatchery) | (juveniles produced / eggs stocked) x 100 | >15% | | Survival rate (grow-out) | (fish harvested / fish stocked) x 100 | >85% | | [Feed conversion ratio](/knowledge/animal-farming/poultry/feed-conversion-ratio-measuring-improving-poultry-efficiency) | total feed fed / total weight gain | 1.0-1.3 | | Specific growth rate | (ln(final weight) - ln(initial weight)) / days x 100 | 0.5-1.0% per day | | Condition factor | (weight / length³) x 100 | 0.8-1.2 | ## Common Failure Patterns ### Hatchery Failures - **Low hatching success**: Caused by poor broodstock nutrition, temperature fluctuations, or bacterial contamination of eggs - **High larval mortality**: Often due to inadequate live feed quality, poor water quality, or bacterial infections - **Cannibalism**: Results from size variation, insufficient feeding frequency, or high stocking density - **Weaning failure**: Occurs when larvae reject formulated diets due to poor palatability or particle size ### Grow-Out Failures - **Chronic low growth**: Caused by suboptimal temperature, poor feed quality, or low-level disease - **Winter mortality**: Fish are stressed by low temperatures and reduced feeding, increasing susceptibility to disease - **Net fouling**: Reduces water exchange and oxygen levels, requiring regular net cleaning - **Escape events**: Result from net damage during storms or predator attacks ### Harvest Failures - **Stress-induced mortality**: Caused by prolonged crowding, rough handling, or temperature shock - **Flesh quality defects**: Gaping, soft texture, or discoloration from stress or delayed chilling - **Regulatory non-compliance**: Results from inadequate withdrawal periods or incomplete records ## Welfare and Safety Context ### Fish Welfare Welfare considerations apply throughout the production cycle. The USDA National Agricultural Library provides resources on animal health and welfare that include aquaculture species [4]. Key welfare indicators for cod include: - Swimming behavior and feeding response - Fin condition and skin integrity - Absence of disease signs - Low mortality rates Stress during handling, transport, and harvest should be minimized through proper equipment, training, and protocols. Welfare issues in capture-based aquaculture highlight the importance of humane slaughter methods [9]. ### Worker Safety Cod farming involves several occupational hazards: - Working on or near water requires life jackets and safety lines - Heavy equipment (cranes, pumps, nets) requires proper training - Cold water and weather exposure requires appropriate clothing - Electrical equipment near water requires ground fault protection Farmers should conduct regular safety training and maintain first aid equipment on site. ### Environmental Considerations Cod farming operations must comply with environmental regulations regarding: - Waste discharge (feed waste, feces) - Chemical use (therapeutants, antifoulants) - Escape prevention and reporting - Interaction with wild fish populations The FAO provides guidance on responsible aquaculture practices through its animal production and health programs [3]. ## Professional Escalation Criteria Farmers should seek professional assistance from veterinarians, aquaculture extension specialists, or regulatory authorities when: 1. **Disease outbreak**: Mortality exceeds 1% per day for two consecutive days, or clinical signs suggest notifiable disease 2. **Water quality crisis**: Dissolved oxygen remains below 4 mg/L despite aeration, or ammonia exceeds 1 mg/L 3. **Structural failure**: Cage damage or mooring failure that risks escape or fish loss 4. **Regulatory issue**: Inspection reveals non-compliance with food safety or environmental regulations 5. **Persistent poor performance**: Feed conversion ratio exceeds 1.5 for three consecutive months, or growth rate is below 50% of target The FAO Fisheries and Aquaculture Department provides species-specific cultivation information that can guide management decisions [1]. The USDA Agricultural Research Service conducts aquaculture research that may inform production practices [2]. ## Feed Management and Feeding Strategy Optimization for Cod Grow-Out Feed represents the largest variable cost in cod farming, typically accounting for 40-60% of total production expenses. Optimizing feeding strategy requires systematic decision-making based on fish behavior, environmental conditions, and growth performance data. This section provides a practical framework for feed management decisions, record-keeping protocols, and troubleshooting feeding problems during the grow-out phase. ### Feed Budget Development and Adjustment A feed budget projects the total feed required for each cage over the production cycle. The budget is calculated using estimated biomass, expected feed conversion ratio (FCR), and target harvest weight. Initial budgets are based on historical performance data from the same site or published benchmarks for Atlantic cod. Feed budget calculation steps: 1. Estimate current biomass from monthly weight samples and mortality records 2. Project daily weight gain using specific growth rate (SGR) targets of 0.5-1.0% per day 3. Calculate daily feed ration as a percentage of body weight 4. Adjust for temperature using a feeding curve that reduces ration at temperatures below 6°C and above 16°C 5. Apply a safety factor of 5-10% to account for feed waste and unexpected growth variation The FAO Fisheries and Aquaculture Department provides species-specific cultivation information that includes feeding guidelines for Atlantic cod [1]. Farmers should compare their feed budgets against these reference values to identify potential overfeeding or underfeeding. Feed budgets must be revised monthly based on actual growth data. If observed growth is 20% below the budget projection for two consecutive months, the feeding strategy requires review. Common causes of growth shortfall include incorrect feed particle size, poor feed palatability, suboptimal feeding frequency, or underlying health problems. ### Feeding Frequency and Timing Decisions Feeding frequency affects feed intake, growth uniformity, and FCR. For cod in sea cages, the following frequency guidelines apply: - Fish under 500 g: 3-4 feedings per day - Fish 500 g to 2 kg: 2-3 feedings per day - Fish over 2 kg: 1-2 feedings per day Feeding timing should align with natural feeding rhythms. Cod are visual feeders that show peak feeding activity during dawn and dusk. Morning feeding should occur within one hour of sunrise, and afternoon feeding should be completed at least two hours before sunset. Feeding during the middle of the day when light intensity is highest often results in reduced feed intake and increased waste. Automatic feeders with demand sensors can improve feeding efficiency. These systems release small amounts of feed when fish strike a trigger mechanism, allowing fish to control intake. Demand feeding reduces feed waste by 10-20% compared to hand feeding, according to operational data from commercial cod farms. However, demand feeders require regular calibration and cleaning to prevent clogging in marine environments. ### Feed Particle Size Management Feed particle size must match fish mouth size to ensure efficient ingestion. Using particles that are too small increases feed waste because fish cannot capture them efficiently. Using particles that are too large reduces intake because fish struggle to swallow them. Particle size guidelines for Atlantic cod: - 50-100 g fish: 2-3 mm pellets - 100-300 g fish: 3-5 mm pellets - 300-800 g fish: 5-7 mm pellets - 800 g to 2 kg fish: 7-9 mm pellets - Over 2 kg fish: 9-12 mm pellets Farmers should transition between particle sizes gradually over 5-7 days. Mixing two adjacent sizes during the transition period helps fish adapt. A sudden change to a larger particle size can cause a 20-30% reduction in feed intake for 3-5 days. ### Feed Waste Monitoring and Correction Feed waste directly reduces profitability and degrades water quality. Uneaten feed accumulates beneath cages, consuming oxygen as it decomposes and releasing ammonia. The USDA Agricultural Research Service conducts aquaculture research that includes studies on feed waste management and environmental impacts [2]. Methods for monitoring feed waste: - Underwater cameras positioned at the feeding zone to observe uneaten pellets - Feed collection trays placed beneath the cage to capture sinking pellets - Observation of feeding behavior: fish should actively compete for feed throughout the feeding period - FCR tracking: a sudden increase in FCR without corresponding growth improvement indicates feed waste If feed waste is detected, corrective actions include: - Reduce ration size by 10-15% and observe intake response - Increase feeding frequency with smaller meals per feeding - Adjust feed particle size if pellets are passing through the cage mesh - Check automatic feeder calibration and distribution pattern - Evaluate water quality, particularly dissolved oxygen, which affects appetite Professional escalation is warranted when feed waste exceeds 5% of total feed input for two consecutive weeks, or when FCR exceeds 1.5 for three consecutive months. These thresholds indicate systemic feeding management problems that require expert assessment. ### Seasonal Feeding Adjustments Water temperature is the primary driver of metabolic rate and feed intake in cod. Seasonal temperature changes require systematic feeding adjustments to maintain growth efficiency. Feeding adjustment guidelines by temperature: - 4-6°C: Feed at 0.5-0.8% body weight per day, once daily - 6-10°C: Feed at 0.8-1.2% body weight per day, 1-2 times daily - 10-14°C: Feed at 1.2-1.8% body weight per day, 2-3 times daily - 14-16°C: Feed at 1.0-1.5% body weight per day, 2 times daily - Above 16°C: Reduce feeding to 0.5-0.8% body weight per day, monitor for stress Winter feeding requires special attention. Cod continue to feed at temperatures as low as 2-3°C, but feed intake drops sharply below 4°C. Farmers should maintain low-level feeding during winter to prevent weight loss and maintain immune function. Complete feed withdrawal for more than 14 days during winter can increase mortality risk when temperatures rise in spring. ### Feed Storage and Quality Management Feed quality degrades over time, particularly in marine environments with high humidity and temperature variation. Proper feed storage preserves nutritional value and palatability. Feed storage protocols: - Store feed in cool, dry conditions below 20°C - Use feed within 4-6 weeks of manufacture during summer - Use feed within 8-12 weeks during winter - Rotate stock using first-in-first-out system - Inspect feed for mold, rancidity, and insect infestation before each use - Seal containers after each use to prevent moisture absorption Rancid feed causes reduced feed intake and can lead to nutritional deficiencies. Signs of rancidity include a sharp or unpleasant odor, darkening of pellet color, and oil separation on the pellet surface. Farmers should reject any feed showing signs of spoilage and notify the supplier immediately. ### Feeding Records and Performance Tracking Systematic feeding records enable data-driven management decisions. The following records should be maintained for each cage: - Daily feed amount offered (kg) - Feed type and particle size - Feeding times and duration - Estimated feed waste (from camera or tray observations) - Water temperature at feeding time - Dissolved oxygen at feeding time - Fish behavior observations (active, sluggish, competitive) - Any feed refusal or abnormal behavior Weekly calculations from feeding records: - Total feed input per cage - Average daily ration as percentage of body weight - Feed conversion ratio (FCR) for the week - Cumulative FCR for the production cycle Monthly feeding performance review should compare actual FCR against the target of 1.0-1.3. If cumulative FCR exceeds 1.4, investigate causes including feed waste, disease, temperature stress, or feed quality issues. The FAO Animal Production and Health program provides resources on feed management and nutrition for aquaculture species [3]. ### Troubleshooting Common Feeding Problems **Problem: Feed refusal (fish stop eating suddenly)** Possible causes and actions: - Low dissolved oxygen: Check oxygen levels immediately. If below 5 mg/L, stop feeding and activate aeration - Temperature shock: Check for rapid temperature changes. Reduce ration until temperature stabilizes - Disease onset: Observe fish for clinical signs. Increase health monitoring frequency - Feed quality issue: Inspect feed for rancidity or contamination. Replace with fresh feed - Algal bloom: Check water clarity and oxygen profile. Reduce feeding until bloom passes **Problem: Uneven growth within cage** Possible causes and actions: - Inadequate feed distribution: Check feeder spread pattern. Add additional feeding points - Size variation: Grade fish to separate size classes. Adjust particle size for smaller fish - Social hierarchy: Increase feeding frequency to allow subordinate fish access to feed - Stocking density too high: Consider splitting cage if density exceeds 20 kg/m³ **Problem: High FCR with adequate growth** Possible causes and actions: - Feed waste: Increase monitoring of uneaten feed. Reduce ration size - Overfeeding: Calculate actual ration as percentage of body weight. Reduce to target level - Feed composition mismatch: Check protein and energy content against fish requirements - Environmental stress: Evaluate temperature, oxygen, and current conditions **Problem: Low FCR with poor growth** Possible causes and actions: - Underfeeding: Increase ration size gradually over 5-7 days - Feed particle size too large: Reduce particle size to match fish mouth size - Nutritional deficiency: Review feed formulation. Consider supplementing with essential fatty acids - Chronic disease: Conduct health assessment. Submit samples for laboratory analysis Professional escalation is required when feeding problems persist for more than two weeks despite corrective actions, or when FCR exceeds 1.6 for two consecutive months. The USDA National Agricultural Library provides resources on animal health and welfare that include guidance on nutrition-related health problems in aquaculture [4]. ## Frequently Asked Questions ### What is the optimal temperature for cod egg incubation? Cod eggs incubate best at 5-7°C with stable salinity of 32-35 ppt. Temperatures above 8°C increase metabolic rate and reduce hatching success. Temperatures below 4°C slow development and increase fungal infection risk. ### How long does it take to grow cod to market size? Atlantic cod typically reach market size of 3-5 kg in 18-24 months from hatch. Growth rate depends on temperature, feed quality, and stocking density. Warmer water (10-14°C) accelerates growth but may increase disease risk. ### What are the main diseases affecting farmed cod? Viral haemorrhagic septicaemia (VHS) is a significant viral disease in cod aquaculture. Bacterial diseases include vibriosis, furunculosis, and atypical Aeromonas infections. Parasitic infections such as sea lice and trichodinids also occur. ### Can cod be farmed in recirculating aquaculture systems? Cod can be raised in recirculating aquaculture systems (RAS) during hatchery and nursery phases. Full grow-out in RAS is technically possible but economically challenging due to high energy costs for temperature control and water treatment. ### What feed is used for cod in aquaculture? Cod require high-protein diets (45-55% crude protein) based on fishmeal and fish oil. Plant-based ingredients can replace some fishmeal but must be supplemented with essential amino acids and fatty acids. Feed particle size increases from 2 mm for juveniles to 12 mm for adults. ### How is cod harvested humanely? Humane harvest methods include live chilling in ice slurry followed by percussive or electrical stunning, or direct stunning without chilling. Both methods should render fish unconscious before bleeding. Stress during crowding should be minimized. ### What records must be kept for cod farming? Farmers must maintain records of broodstock source, egg production, larval survival, feed input, growth measurements, mortality, water quality, treatments, and harvest data. These records support management decisions and regulatory compliance. ### Is cod farming economically viable? Economic viability depends on production costs, market prices, and scale. Norway's cod farming industry has experienced periods of growth and contraction. Factors affecting profitability include feed costs, survival rates, and market demand for farmed cod. ## Related Farming Guides - [Fish Farming Water Feed Stocking Biosecurity Welfare And Harvest Decisions](/knowledge/animal-farming/aquaculture/fish-farming-water-feed-stocking-biosecurity-welfare-and-harvest-decisions) - [Freshwater Prawn Farming Stocking Shelter Feeding And Harvest Management](/knowledge/animal-farming/aquaculture/freshwater-prawn-farming-stocking-shelter-feeding-and-harvest-management) - [Aquaponics Fish Health And System Management](/knowledge/animal-farming/aquaculture/aquaponics-fish-health-and-system-management) - [Shrimp Farming Biosecurity Water Management And Crop Observation](/knowledge/animal-farming/aquaculture/shrimp-farming-biosecurity-water-management-and-crop-observation) - [Raceway Fish Farm Management Flow Solids Feeding And Emergency Response](/knowledge/animal-farming/aquaculture/raceway-fish-farm-management-flow-solids-feeding-and-emergency-response) ## 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. - [Vaccines for fish in aquaculture.](https://pubmed.ncbi.nlm.nih.gov/15757476). Expert review of vaccines, 2005. - [Forage fish for cod and people.](https://pubmed.ncbi.nlm.nih.gov/33574042). Proceedings of the National Academy of Sciences of the United States of America, 2021. - [Status and future perspectives of vaccines for industrialised fin-fish farming.](https://pubmed.ncbi.nlm.nih.gov/23769873). Fish & shellfish immunology, 2013. - [Viral haemorrhagic septicaemia virus in marine fish and its implications for fish farming--a review.](https://pubmed.ncbi.nlm.nih.gov/16266325). Journal of fish diseases, 2005. - [Animal Welfare Issues in Capture-Based Aquaculture.](https://pubmed.ncbi.nlm.nih.gov/33808163). Animals : an open access journal from MDPI, 2021. - [Large-scale sequence analyses of Atlantic cod.](https://pubmed.ncbi.nlm.nih.gov/19491044). New biotechnology, 2009. - [Is capture-based aquaculture viable? The case of Atlantic cod in Norway](https://doi.org/10.1016/j.aquaculture.2023.739520). Aquaculture, 2023. - [Norway’s cod farming industry: Adaptation, imitation or innovation?](https://doi.org/10.4324/9780429046773-3). Aquacultural Development Social Dimensions of an Emerging Industry, 2019. > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.