Aquaculture Midterm Coverage PDF

SURVEY OF AQUACULTURE SYSTEMS IN THE PHILIPPINES ABE PC 419/419L Freshwater Aquaculture Systems Freshwater ponds - enclosed, man- made or natural water bodies where fish and other aquatic species are raised in a controlled environment. These systems are commonly used in rural and ag...

SURVEY OF AQUACULTURE SYSTEMS IN THE PHILIPPINES ABE PC 419/419L Freshwater Aquaculture Systems Freshwater ponds - enclosed, man- made or natural water bodies where fish and other aquatic species are raised in a controlled environment. These systems are commonly used in rural and agricultural areas due to their relatively simple design and management. Freshwater Aquaculture Systems Species Cultured Nile Tilapia (Oreochromis niloticus): One of the most commonly farmed fish in the Philippines due to its fast growth, high yield, and adaptability to varying water conditions. Catfish (Clarias batrachus): Known for its resilience and ability to thrive in low-oxygen environments, making it suitable for farming in ponds with lower water exchange. Freshwater Prawn (Macrobrachium rosenbergii): Valued for its high market price, prawn farming in ponds can be integrated with fish species like tilapia (polyculture) to maximize pond productivity. Freshwater Aquaculture Systems Characteristics of Freshwater Ponds Size and Depth: Ponds typically range from small backyard setups to large commercial operations, with depths varying between 1 to 3 meters. Water Source: Ponds are generally filled with water from nearby rivers, lakes, or wells, with water flow being controlled to maintain quality. Stocking Density: The stocking rate depends on species and culture method (extensive, semi-intensive, or intensive). Tilapia, for example, is commonly stocked at high densities in semi-intensive and intensive systems. Freshwater Aquaculture Systems Geographical Distribution Luzon: Major freshwater aquaculture activities are concentrated in Central Luzon (e.g., Pampanga, Nueva Ecija), where vast areas of agricultural land are converted into fishponds. Mindanao: Regions like Lanao del Norte and Davao have growing freshwater aquaculture industries due to favorable water conditions and government support. Visayas: Iloilo and Cebu are emerging areas for freshwater aquaculture, particularly tilapia farming, benefiting from community-based aquaculture initiatives. Freshwater Aquaculture Systems Benefits of Freshwater Aquaculture Accessibility: Freshwater ponds are often accessible to small-scale farmers, requiring minimal investment and offering a sustainable income source. Flexibility: These systems allow for diverse farming options, from monoculture to polyculture (e.g., combining fish and prawns). Environmental Control: Farmers can manage water quality, feeding, and disease prevention more easily in ponds than in open water systems. Brackishwater Aquaculture Systems Brackishwater Fishponds - aquaculture systems located in coastal areas where freshwater from rivers or streams mixes with saltwater from the sea, creating a low-salinity environment. These ponds are widely used for farming species that thrive in such conditions, such as milkfish (Chanos chanos) and shrimp (Penaeus species). Brackishwater Aquaculture Milkfish (ChanosSystems Species Cultured chanos): The Philippines is one of the top producers of milkfish globally. This species is highly favored in brackishwater ponds due to its ability to adapt to varying salinity levels and its fast growth. It is a staple in the Filipino diet, making its production critical for both local consumption and export. Shrimp (Penaeus monodon, P. vannamei): Shrimp farming, particularly for species like the black tiger prawn (P. monodon) and the whiteleg shrimp (P. vannamei), is a major component of the Philippine aquaculture industry. Shrimp are farmed in both extensive and intensive systems, often in ponds with controlled water exchange.  Brackishwater Aquaculture Systems Characteristics of Brackishwater Fishponds Location: These ponds are usually situated in coastal lowlands, mangrove areas, or tidal flats. Their proximity to both freshwater and seawater sources allows for the careful regulation of salinity levels, which is essential for optimal species growth. Water Management: Effective water management is crucial in brackishwater aquaculture. Ponds rely on tidal exchange or pumps to bring in seawater and remove waste water, maintaining ideal water quality for the species being farmed. Pond Size and Depth: Brackishwater ponds are generally larger than freshwater ponds, with sizes ranging from 1 to 10 hectares and depths between 0.5 to 2 meters, depending on the species cultured and the farming method (extensive, semi-intensive, or intensive).  Brackishwater Aquaculture Systems Importance in Coastal Areas Livelihood and Employment: Brackishwater fishponds provide significant employment opportunities for coastal communities, supporting thousands of families involved in fish and shrimp farming. Contribution to Food Security: Milkfish and shrimp are high-demand commodities, both domestically and internationally. Brackishwater aquaculture ensures a steady supply of these species, contributing to food security and economic stability in coastal regions. Integration with Mangrove Ecosystems: In many areas, brackishwater aquaculture is integrated with mangrove restoration projects. Mangroves not only provide natural barriers against storm surges and coastal erosion but also enhance the ecological sustainability of fishponds by improving water quality and providing habitat for juvenile aquatic species.  Brackishwater Aquaculture Systems Role in Philippine Aquaculture Economic Importance: Brackishwater aquaculture is a cornerstone of the Philippine aquaculture industry, particularly in regions such as the Ilocos Region, Western Visayas, and Central Luzon. The production of high-value species like shrimp has significant export potential, contributing to foreign exchange earnings and enhancing the economic status of coastal areas. Sustainability and Challenges: While brackishwater aquaculture plays a vital role, it faces challenges such as overuse of water resources, environmental degradation (e.g., destruction of mangroves), and disease outbreaks, particularly in shrimp farming. Sustainable practices, such as integrated coastal management and the use of biosecure systems, are essential to address these issues.  Brackishwater Aquaculture Systems Benefits of Brackishwater Aquaculture High Yield Potential: Brackishwater ponds offer high production potential due to favorable environmental conditions, which promote faster growth and higher yields, especially for species like milkfish and shrimp. Versatility: These systems can be adapted to raise a variety of species, making them a flexible option for aquaculture in coastal regions. Economic Diversity: In addition to local food production, brackishwater aquaculture contributes significantly to export revenues, especially from shrimp farming. Marine Aquaculture Systems Cage culture - a marine aquaculture system where fish are raised in large cages or enclosures submerged in coastal waters or open seas. These cages are designed to contain the fish while allowing water to flow freely through the structure, maintaining water quality and simulating a natural environment.  Marine Aquaculture Systems Species Cultured Groupers (Epinephelus spp.): Groupers are high-value fish prized for their delicate flavor and high market demand, especially in international markets like Hong Kong and China. Groupers thrive in cage culture systems, where water quality and feeding can be closely monitored.  Marine Aquaculture Systems Species Cultured Red Snappers (Lutjanus argentimaculatus): Another high-value species raised in marine cages, snappers are popular for their fast growth rates and demand in both local and export markets. They are often farmed alongside other species to optimize space and production in cage culture systems.  Marine Aquaculture Systems Characteristics of Cage Culture Location: Cages are typically deployed in calm, sheltered areas such as bays, fjords, and coastal inlets. These locations provide protection from harsh weather conditions and strong currents, while still allowing adequate water exchange to maintain the health of the cultured species. Structure: Cages can be made from durable materials like high-density polyethylene (HDPE) or metal, and are either anchored to the seabed or floated on the surface. The size of the cages can vary, with diameters ranging from 10 to 20 meters or more, depending on the species being cultured and the available space. Stocking Density: Cage culture systems allow for high stocking densities, which increases production efficiency. However, careful management of stocking levels is essential to prevent overcrowding, stress, and disease outbreaks in the fish.  Marine Aquaculture Systems Importance of Cage Culture in Philippine Aquaculture Economic Value: Cage culture is a growing sector in Philippine aquaculture, especially for high-value species like groupers and snappers. The ability to raise these species in controlled environments allows farmers to meet local and international demand for premium seafood, generating substantial income. Environmental Sustainability: While cage culture has high production potential, it must be managed carefully to avoid environmental impacts, such as nutrient pollution and the spread of diseases. Implementing best practices, such as proper waste management and site rotation, can help minimize these risks. Marine Aquaculture Systems Seaweed Farming - involves cultivating different species of seaweed, such as Eucheuma and Kappaphycus, in coastal waters. Seaweed is grown on ropes or nets submerged in shallow areas, where it absorbs nutrients from the surrounding water and sunlight to grow. This farming method is relatively low-impact and sustainable compared to other forms of aquaculture.  Marine Aquaculture Systems Contribution to Local Economies Livelihood for Coastal Communities: Seaweed farming is an important source of livelihood for many coastal communities in the Philippines, particularly in regions like Tawi-Tawi, Zamboanga Peninsula, and Palawan. It provides an accessible means of income for small-scale farmers, requiring low startup costs and minimal maintenance. Women’s Participation: Seaweed farming is often a family-based activity, with women playing a significant role in harvesting and processing the seaweed, thus contributing to gender empowerment and community development. Income Stability: Seaweed has consistent demand in both local and global markets, making it a reliable source of income for farmers. It is used in various industries, including food, cosmetics, pharmaceuticals, and as a raw material for carrageenan, an important thickening agent in  Marine Aquaculture Systems Export Market and Global Demand Carrageenan Industry: The Philippines is one of the world's largest producers of carrageenan, a gel-like substance extracted from seaweed. Carrageenan is used in a wide range of products, including dairy products, toothpaste, and cosmetics. The export of seaweed and carrageenan is a significant contributor to the national economy. Sustainability and Environmental Benefits: Seaweed farming is a sustainable practice that contributes to the health of marine ecosystems. Seaweed absorbs carbon dioxide and excess nutrients from the water, helping to mitigate the effects of ocean acidification and eutrophication. Additionally, seaweed farms provide habitat for marine life, promoting biodiversity.  Marine Aquaculture Systems Role in Marine Aquaculture Integration with Other Systems: Seaweed farming is often integrated with other marine aquaculture practices, such as fish and shellfish farming. In Integrated Multi-Trophic Aquaculture (IMTA), seaweed is used to absorb excess nutrients generated by fish farming, creating a balanced and sustainable ecosystem. Climate Resilience: Seaweed farming is resilient to changes in climate and can be an adaptable livelihood for coastal communities affected by climate change. Its ability to grow in a variety of water conditions makes it an important component of climate-adaptive aquaculture strategies. Benefits of Marine Aquaculture Systems High-Value Production: Cage culture provides opportunities to farm premium species like groupers and snappers, while seaweed farming boosts the local economy and contributes to international markets. Sustainability: Seaweed farming enhances marine health and promotes ecological balance, while sustainable cage culture practices help reduce environmental impacts. Livelihood and Food Security: Both cage culture and seaweed farming play a crucial role in supporting livelihoods in coastal communities and contributing to local food security.  REVIEW OF BASIC BIOLOGICAL CHARACTERISTICS OF IMPORTANT AQUACULTURE SPECIES ABE PC 419/419L  Selection Criteria for Aquaculture 1 Species GROWTH RATE - refers to how quickly an aquatic species reaches market size, which directly impacts production cycles, profitability, and resource efficiency. Fast-growing Species: In aquaculture, species with fast growth rates are preferred because they reduce the time and resources needed to reach harvestable size, thus increasing overall productivity. Tilapia - one of the most popular species for aquaculture due to its rapid growth and ability to reach market size in just 4 to 6 months. Its adaptability to a wide range of environmental conditions also makes it a favored choice for both small- and large-scale farms. Milkfish (Bangus) - known for its fast growth in brackishwater and marine environments, milkfish can reach marketable size within 6 to 8 months, making it one of the staple species in Philippine aquaculture. Its fast growth ensures that farmers can harvest more frequently, maximizing yield.  Selection Criteria for Aquaculture Species 2 DISEASE RESISTANCE- the ability of a species to withstand or recover from diseases and environmental stresses, such as poor water quality or fluctuating temperatures. Species with High Disease Resistance: Aquaculture species that are resilient to common diseases and environmental stresses are more profitable since they reduce the need for intensive management, medication, or frequent water quality adjustments. Tilapia - widely regarded for its hardiness and resistance to diseases, particularly in suboptimal water conditions. Its ability to survive in low-oxygen environments and tolerate poor water quality makes it a robust choice for farmers. Catfish - known for its resilience, catfish is another species that can thrive in low- oxygen or high-ammonia conditions, making it less vulnerable to the challenges that often lead to disease outbreaks in more sensitive species. Milkfish - although milkfish can be affected by environmental stresses, its overall disease resistance is strong, especially in controlled brackishwater environments.  Selection Criteria for Aquaculture 3 MARKET DEMAND- refers to Species consumer preferences and the commercial viability of a species. Species that are in high demand offer better opportunities for profit, making their farming a key focus for aquaculture operations. High-demand Species: Aquaculture species that are in constant demand in local and export markets are prioritized to ensure profitability. Market trends, export opportunities, and consumer preferences shape the selection of species for farming. Prawns (Shrimp) - particularly Penaeus monodon (black tiger prawn) and Penaeus vannamei (whiteleg shrimp), are highly sought after in both local and international markets. Shrimp farming is a lucrative industry, with significant demand for high-quality prawns in global seafood markets, making them an attractive species for aquaculture ventures. Milkfish - a staple in the Filipino diet and enjoys high local market demand. In addition, it is exported to international markets such as the Middle East, where it is consumed by the Filipino diaspora. Its consistent demand makes milkfish farming a highly profitable venture. Tilapia - widespread acceptance and relatively low market price make it one of the most commonly farmed and consumed species in the world. It has a high demand in local markets for everyday consumption and is gaining popularity in export markets, particularly in the U.S.  Selection Criteria for Aquaculture 4 Species OTHER CRITERIA TO CONSIDER Feed Efficiency: Species that efficiently convert feed into body mass (high feed conversion ratio, or FCR) are economically favorable since feed is often the most significant expense in aquaculture operations. Tilapia and milkfish have relatively low FCRs, making them cost-effective species to farm. Reproduction: Aquaculture species that reproduce easily in captivity reduce the need for wild broodstock, ensuring a steady supply of juveniles for farming. Species like tilapia breed readily in captivity, while species like shrimp require specialized hatchery conditions. Environmental Impact: Species that have minimal impact on the environment, either due to their ability to thrive in low-intensity systems (e.g., seaweed, filter-feeding bivalves) or their sustainability in integrated aquaculture systems, are becoming increasingly important in the context of sustainable aquaculture practices. Production Cycles of Selected Aquaculture Species Production Cycle Overview Key Stages in the Life Cycle Fry: This is the earliest stage of life for most fish species, immediately after hatching. Fry are small, fragile, and require special care, usually in a hatchery or nursery. The fry stage is characterized by rapid growth, and they need adequate nutrition and protection from environmental stresses. Juvenile: After the fry stage, fish grow into juveniles, which are more resilient but still require proper environmental conditions and feed. During this phase, they are usually transferred to larger enclosures or grow-out ponds for further development. Grow-Out: The grow-out phase is where the fish grow to marketable size. This stage typically involves transferring fish to ponds, cages, or other large production systems where they are fed and managed intensively until they Production Cycles of Selected Aquaculture Species Production Cycle Overview Key Stages in the Life Cycle Production Cycles of Selected Aquaculture Species Production Cycle Overview Tilapia: From Breeding to Market Size Breeding: Tilapia are known for their rapid reproduction in captivity. Breeding occurs in controlled environments like hatcheries or ponds, where broodstock (adult fish used for reproduction) are kept. Females lay eggs in nests, and males fertilize them. In many cases, the eggs are collected and artificially incubated to increase survival rates. Fry to Juvenile Stage: Once the eggs hatch, fry are reared in tanks or nursery ponds. During this stage, they are given high-protein feed to ensure fast growth. Tilapia fry are hardy and grow quickly, reaching juvenile stage in a few weeks. Grow-Out: Juvenile tilapia are transferred to larger grow-out ponds or cages where they are raised to market size. This stage typically lasts between 4 to 6 months, depending on environmental conditions and feeding regimes. Tilapia Production Cycles of Selected Aquaculture Species Production Cycle Overview Milkfish: Hatchery, Nursery, and Grow-Out Phases Hatchery Phase: Milkfish breeding is typically done in hatcheries, where broodstock are maintained to spawn fertilized eggs. Hatcheries provide controlled conditions for the eggs to hatch and the larvae to grow into fry. This phase requires precise control of water quality, temperature, and feeding to maximize survival. Nursery Phase: After hatching, milkfish fry are transferred to nursery ponds or tanks where they are raised until they become juveniles. This phase lasts for about 1 to 2 months, during which the fry are given finely ground feeds to promote fast growth and development. Grow-Out Phase: Juvenile milkfish are then moved to larger grow-out ponds, brackishwater ponds, or marine cages. The grow-out phase lasts 6 to 8 months, during which the fish are fed regularly and monitored for growth.  Production Cycles of Selected Aquaculture Species Prawn (Shrimp) Production Cycle Life Cycle: Hatchery Stage: Grow-Out Stage: Importance of Water The life cycle of prawns, Prawn hatcheries play a Postlarvae are transferred Quality: such as the black tiger critical role in producing to grow-out ponds, where Throughout all stages of prawn (Penaeus postlarvae for farming. they are raised to the prawn production monodon) or whiteleg Hatcheries provide a marketable size (15-25 cycle, maintaining shrimp (Penaeus controlled environment grams for shrimp). The optimal water quality is vannamei), starts with for eggs to develop into grow-out stage lasts 4 to 6 crucial. Poor water eggs that hatch into larvae and then into months, and during this conditions can lead to larval stages (nauplius, postlarvae. Water quality time, careful management disease outbreaks, slow of feeding and water zoea, and mysis). After management (e.g., growth, and increased quality is essential to the larval stage, they salinity, temperature) is mortality. ensure good growth and develop into postlarvae, crucial at this stage to prevent disease. Prawns which are more robust ensure high survival are highly sensitive to and can be transferred to rates. water parameters, so grow-out ponds. regular monitoring of  Production Cycles of Selected Aquaculture Species Prawn (Shrimp) Production Cycle  Production Cycles of Selected Aquaculture Species Catfish Production Cycle Life Cycle: The catfish production cycle starts with spawning, where female catfish lay eggs in nests or tanks. These eggs are fertilized by males and hatch into fry. Hatchery Stage: Hatcheries are used to incubate eggs and rear catfish fry in controlled conditions. Once hatched, the fry are kept in nursery tanks or ponds where they are fed and allowed to grow into juveniles. Catfish fry are relatively resilient but still require proper feeding and water management. Grow-Out Stage: Juvenile catfish are then transferred to grow-out ponds or tanks, where they are fed and managed until they reach marketable size (usually 300 grams to 1 kilogram). Catfish are known for their fast growth and ability to thrive in less-than-ideal water conditions, such as low oxygen or higher ammonia levels. Role of Hatcheries: Hatcheries play an important role in ensuring a steady supply of fry and juveniles for catfish farming. By controlling the breeding environment, hatcheries can improve survival rates and enhance growth performance. Importance of Water Quality: While catfish are hardy and can tolerate poor water quality better than most species, maintaining good water conditions still leads to faster growth and higher yields. Regular monitoring of water parameters such as dissolved oxygen, ammonia, and pH is crucial  Environmental and Water Quality Requirements OPTIMAL ENVIRONMENTAL PARAMETERS Temperature Temperature is a key environmental factor that affects metabolic rates, growth, reproduction, and overall health of aquaculture species. Optimal Ranges for Different Species: Each species has a specific temperature range in which it thrives. Deviations from this range can slow growth, increase stress, or even lead to mortality. ⚬ Tilapia: The optimal temperature range for tilapia is 25°C to 30°C. At these temperatures, their metabolism and growth rates are highest. Temperatures below 20°C slow their growth and make them more susceptible to diseases, while temperatures above 35°C can be lethal. ⚬ Milkfish (Bangus): Milkfish thrive in warm tropical waters, with an optimal temperature range of 26°C to 32°C. Lower temperatures can slow their growth, while  Environmental and Water Quality Requirements OPTIMAL ENVIRONMENTAL PARAMETERS DISSOLVED OXYGEN Dissolved oxygen (DO) is the amount of oxygen available in water for fish and other aquatic organisms to breathe. DO is critical for respiration, and low levels can lead to stress, poor growth, or mortality. Importance for Species Survival: Different species have varying requirements for dissolved oxygen. Maintaining adequate levels is crucial, especially in high-density farming systems where oxygen demand is high. ⚬ Prawns (Shrimp): Prawns are highly sensitive to dissolved oxygen levels. The optimal DO level for prawns is above 5 mg/L. Levels below this can cause stress, reduced feed intake, and slower growth. Oxygen levels below 2 mg/L can lead to mass mortality. ⚬ Tilapia: Tilapia are relatively hardy and can survive in low-oxygen environments (as low as 2-3 mg/L), but their optimal growth occurs when DO levels are around 5-7 mg/L.  Environmental and Water Quality Requirements WATER QUALITY MONITORING KEY TOOLS AND TECHNIQUES Water Testing Kits: These are used to measure key water quality parameters such as pH, ammonia, nitrite, nitrate, and dissolved oxygen. Regular testing helps farmers monitor and maintain optimal water conditions for aquaculture species. Dissolved Oxygen Meters: A DO meter is essential for monitoring the oxygen levels in water, especially in high-density farming systems where oxygen depletion can occur rapidly. pH Meters: A pH meter is used to measure the acidity or alkalinity of water. It is important to keep the pH within the optimal range for the species being cultured. Ammonia and Nitrite Test Kits: Ammonia and nitrite are toxic byproducts of fish waste and decomposing organic matter. Monitoring these levels is crucial because high concentrations can cause stress, poor growth, and even death.  Environmental and Water Quality Requirements WATER QUALITY MONITORING IMPORTANCE OF MAINTAINING PH, AMMONIA, AND Nitrogen Levels pH: The pH of the water affects the solubility and toxicity of chemicals, such as ammonia. Most aquaculture species thrive in water with a pH range of 6.5 to 8.5. For example: ⚬ Tilapia: Tolerates a wide pH range but grows best when the pH is between 6.5 and 8.5. ⚬ Prawns: Require a pH range of 7.0 to 8.5. A pH that is too acidic or too alkaline can stress prawns and lead to poor growth and susceptibility to diseases. Ammonia (NH3): Ammonia is a toxic nitrogen compound that results from the breakdown of organic matter and fish waste. High ammonia levels are dangerous for all aquaculture species as they interfere with respiration and can cause death. ⚬ Safe Ammonia Levels: Ideally, ammonia levels should be below 0.05 mg/L for most species. Even low levels of ammonia can cause stress, while levels above 0.5 mg/L can be lethal.  Environmental and Water Quality Requirements WATER QUALITY MONITORING IMPORTANCE OF MAINTAINING PH, AMMONIA, AND Nitrogen Levels Nitrogen Compounds (Nitrite and Nitrate): Nitrite (NO2) is toxic to fish and can cause nitrite poisoning (brown blood disease), while nitrate (NO3) is less toxic but should still be monitored in recirculating systems. ⚬ Nitrite: Should be kept below 0.1 mg/L to prevent toxicity. ⚬ Nitrate: Although less harmful, nitrate levels should ideally be kept below 50 mg/L to avoid long-term stress on fish and prawns.  Culture Practices for Tilapia and Milkfish EXTENSIVE, SEMI-INTENSIVE, AND INTENSIVE CULTURE METHODS Extensive Culture: Description: This method involves low stocking densities and minimal input, relying primarily on natural food sources like plankton and detritus in ponds or bodies of water. There is little to no artificial feeding, and the growth rate of fish is slower compared to more intensive systems. Application: Common in rural areas with large available land or bodies of water, extensive systems are mainly used by small-scale farmers due to low cost. However, the yield per hectare is relatively low. Example: Tilapia and milkfish grown in natural ponds, relying on the natural productivity of the water for their food.  Culture Practices for Tilapia and Milkfish EXTENSIVE, SEMI-INTENSIVE, AND INTENSIVE CULTURE METHODS Semi-intensive Culture: Description: This method involves moderate stocking densities and partial reliance on both natural food and supplemental feeding. Fertilizers may be used to enhance natural food production, and commercial feeds are used to boost fish growth. Application: Semi-intensive systems are more efficient in terms of space and yield compared to extensive methods, and they are widely used in commercial aquaculture. Pond management practices are crucial, including regular water exchange and fertilization. Example: Tilapia and milkfish ponds that are fertilized and supplemented with formulated feeds. Stocking densities range from 5,000 to 10,000 fish per hectare for tilapia.  Culture Practices for Tilapia and Milkfish EXTENSIVE, SEMI-INTENSIVE, AND INTENSIVE CULTURE METHODS Intensive Culture: Description: This method is characterized by high stocking densities, complete reliance on commercial feeds, and frequent monitoring and management of water quality. Intensive systems require aeration, water exchange, and disease control to manage high-density environments. Application: Used for large-scale, commercial production where maximizing output per unit area is essential. Intensive systems have higher operational costs but yield significantly more fish per hectare than semi-intensive or extensive systems. Example: Tilapia and milkfish cultured in tanks, cages, or highly managed ponds with controlled feed rations, aeration, and water exchange. Stocking densities in intensive systems can exceed 20,000 fish per hectare for tilapia.  Culture Practices for Tilapia and Milkfish STOCKING DENSITIES, FEEDING PRACTICES, AND DISEASE MANAGEMENT STOCKING DENSITIES: Tilapia: In semi-intensive systems, stocking densities range from 5,000 to 10,000 fish per hectare. In intensive systems, densities can go as high as 20,000 to 30,000 fish per hectare. Milkfish: Milkfish can be stocked at 5,000 to 15,000 fish per hectare in semi-intensive systems and up to 50,000 fish per hectare in intensive systems like marine cages. Feeding Practices: Natural Feed: In extensive and semi-intensive systems, fish rely on the natural productivity of ponds, such as algae, plankton, and organic matter. Supplemental Feeding: Semi-intensive systems use supplemental feeds to boost growth. Commercial pellet feeds are often introduced when natural feed becomes insufficient. Complete Feeds: Intensive systems depend entirely on formulated feeds to ensure rapid growth. Feeds are specifically designed to meet the nutritional requirements of tilapia and milkfish at different stages of growth.  Culture Practices for Tilapia and Milkfish STOCKING DENSITIES, FEEDING PRACTICES, AND DISEASE MANAGEMENT DISEASE MANAGEMENT: Tilapia: Disease management in tilapia culture involves maintaining good water quality, reducing stress, and using probiotics or antibiotics when necessary. Common diseases include Streptococcus and Aeromonas infections, which are often triggered by poor water conditions or high stocking densities. Milkfish: Disease outbreaks in milkfish ponds can be minimized through proper water management and stocking practices. Vibriosis is a common bacterial disease in milkfish farming, especially in brackishwater environments.  CULTURE PRACTICES FOR PRAWNS AND CATFISH Water Exchange and Aeration Practices Water Exchange: Prawns (Shrimp): Water exchange is critical in prawn farming to maintain optimal water quality, prevent the build-up of toxic substances like ammonia, and ensure that the prawns have enough oxygen. Farmers typically perform 10-20% water exchange daily in semi-intensive and intensive systems. In highly intensive systems, recirculating aquaculture systems (RAS) may be used to filter and reuse water. Catfish: Catfish are relatively hardy but still benefit from regular water exchange, especially in high-density farming systems. For optimal growth, water exchange is done to control waste build-up and maintain oxygen levels. In smaller systems, partial water exchanges are conducted weekly.  CULTURE PRACTICES FOR PRAWNS AND CATFISH Water Exchange and Aeration Practices Aeration: Prawns: Aeration is vital in shrimp ponds to maintain dissolved oxygen levels. Paddlewheel aerators or diffused aeration systems are commonly used in semi- intensive and intensive shrimp farms. Aeration ensures that prawns have sufficient oxygen, particularly at night when oxygen levels drop. Catfish: While catfish are more tolerant of low oxygen levels, intensive systems still require aeration to enhance growth rates and prevent stress. Paddlewheel or airlift aerators are used to keep oxygen levels stable, especially during feeding times when oxygen demand spikes.  CULTURE PRACTICES FOR PRAWNS AND CATFISH Disease Prevention and Control in Different Farming Systems Prawns (Shrimp): Common Diseases: Prawns are susceptible to viral infections such as White Spot Syndrome Virus (WSSV) and Yellowhead Disease, which can cause mass mortality. Bacterial infections like vibriosis are also common. Prevention Strategies: Good water quality management, biosecurity measures (e.g., screening broodstock for diseases), and the use of probiotics or immunostimulants can help prevent diseases. Water quality monitoring for parameters like ammonia, nitrite, and salinity is crucial for minimizing stress on prawns. Vaccines: Some farms use vaccines to prevent specific diseases, while others may employ strict quarantine and treatment protocols for infected ponds.  CULTURE PRACTICES FOR PRAWNS AND CATFISH Disease Prevention and Control in Different Farming Systems Catfish: Common Diseases: Catfish are prone to bacterial diseases such as Columnaris and Edwardsiella, especially in high-density systems. Parasitic infestations, such as those caused by Ichthyophthirius (Ich), are also common. Prevention Strategies: Disease prevention in catfish farming includes maintaining water quality, minimizing stress, and using antibiotics or probiotics as preventive measures. Vaccination is available for some bacterial diseases like Edwardsiella. Biosecurity: Implementing biosecurity measures, such as disinfection of equipment and proper sanitation practices, helps to reduce the spread of pathogens.  SUMMARY Overview of Aquaculture Systems in the Philippines: ⚬ Freshwater systems (e.g., ponds for tilapia, catfish). ⚬ Brackishwater systems (e.g., fishponds for milkfish and prawns). ⚬ Marine systems (e.g., cage culture for groupers and snappers, seaweed farming). Importance of Biological Characteristics: ⚬ Selection of species based on growth rate, disease resistance, and market demand (e.g., tilapia, milkfish, prawns). ⚬ Understanding life cycles and production cycles for effective management. Environmental Management for Successful Aquaculture: ⚬ Maintaining optimal water quality (temperature, dissolved oxygen, salinity). ⚬ Regular water quality monitoring (pH, ammonia, nitrite). ⚬ Sustainable practices to ensure long-term viability and production efficiency. Key Takeaways: ⚬ Proper selection of species and culture systems leads to efficient and profitable aquaculture. ⚬ Effective environmental management and disease control are critical for sustaining productivity. ⚬ Aquaculture’s role in contributing to food security and local economies is significant.