Anyone involved in the aquaculture industry is likely familiar with the three distinct phases that define fish farming: fingerling, rearing, and fattening. Each phase presents unique challenges and requires tailored approaches to ensure successful cultivation. Proper nutrition is equally crucial, as dietary needs vary depending on the developmental stage of the fish.
For optimal control over each phase of the fish lifecycle, it's advisable to conduct these processes in separate facilities or highly controlled environments. This approach helps create ideal conditions for fish growth and development. In this blog post, we'll delve into the specifics of fingerling, rearing, and fattening, exploring how fish should be fed during each stage. Additionally, we’ll touch upon the breeding times of some prominent species and what factors influence these durations.
Fingerling: A Critical Phase Requiring Diligent Care
The fingerling phase marks the initial stage of fish development, occurring when they are still juveniles. This phase typically takes place in specialized farms to enhance efficiency. Once the fingerlings reach an appropriate size and weight, they're sold to other farms or facilities where they move on to the subsequent stages—rearing and fattening.
Prior to entering the fingerling phase, during the larval stage, fish hatch from eggs and, measuring just millimeters, rely on internal energy reserves rather than external food. Because of their small size and fragility, they remain in incubators until they learn to swim.
The larval phase varies across species, lasting roughly a week for most tropical fish. Following this period, fish transition into the post-larval stage, where they are counted and redistributed to external hatcheries or intensive fingerling tanks.
Fingerling is a critical phase, particularly concerning feeding. Due to their diminutive size, fingerlings have limited dietary options. Conversely, their small stature makes them vulnerable to predators like aquatic insects and other fish species. Moreover, fingerlings face competition for food from tadpoles and smaller fish.
Consequently, fingerlings must primarily consume plankton, which includes microorganisms found in the water column, and benthos, microorganisms residing on the substrate. Certain species, such as tilapia, begin consuming inert food (ration) as soon as they open their mouths. This feeding regimen continues until the fish can consume other types of food. This method is commonly applied to native species like tambaqui, pintado, and golden fish.
Options for Fingerling Production
Several systems can be employed for fingerling production, including semi-intensive, intensive, and extensive setups.
1) Semi-Intensive Fingerling Production
In semi-intensive fingerling production, the most widely adopted system, hatcheries require hydraulic equipment for comprehensive water flow management to facilitate efficient handling. This system involves critical components such as complete drying, mud removal, predator elimination, liming, and fertilization to boost phytoplankton and zooplankton production.
Water quality must be meticulously monitored through physical and chemical analyses.
2) Intensive Fingerling Production
Intensive fingerling production represents a more recent and evolving system in many fish farms. Its primary aim is to establish a closed system that safeguards against predator intrusion. Operated in laboratories, this system demands continuous human intervention due to its high level of control, making it more expensive. However, it offers the advantage of achieving high survival rates and substantial fingerling yields.
3) Extensive Fingerling Production
Another developing system is the extensive approach, where family or community hatcheries receive post-larval animals. The focus here is to manage predator populations both before and during the process. While this method can only be used for specific species and at lower densities due to environmental limitations and food organism availability, it presents challenges in predator eradication, given the lack of flow control.
Rearing: Transitioning Fingerlings to Juvenile Fish
Once fingerlings reach the desired size for sale to other farms, they enter the rearing phase. During this stage, fingerlings grow into juvenile fish. Rearing can occur independently, meaning farms specialize in raising fingerlings until they reach the juvenile stage, after which they are sold to other farms for fattening/termination. Alternatively, rearing can happen concurrently with the final fattening phase.
When rearing is done independently, fingerlings are directly purchased from specialized hatcheries. They are then transferred to rearing farms, where they stay until reaching the juvenile stage. Finally, they are sent to specialized termination farms.
Termination: The Final Stage Before Commercialization
During this phase, fish reach adulthood and are marketed to consumers. In some farms, the ideal size for starting termination is 5 cm, though this can vary significantly based on species traits and seasonal factors. This size ensures better efficiency in ingesting larger particles like farinaceous foods, small insects, and other similar items. Additionally, it enhances their ability to evade predators.
Termination focuses on increasing fish size until they reach the commercial weight, which can exceed 5 kg depending on the species. Consequently, this phase demands larger quantities of food, necessitating precise daily feeding schedules and consistent monitoring of production.
Nutritional Needs of Fish
Certain nutrients must be included in fish feed to ensure healthy development and robust growth throughout all stages of farming, especially during the termination phase, where dietary reinforcement is most critical.
Protein content varies according to species and lifecycle stage. Regardless of the protein source, the 10 essential amino acids must be present:
- Methionine
- Arginine
- Threonine
- Tryptophan
- Hisitidine
- Isoleucine
- Lysine
- Leucine
- Valine
- Phenylalanine
Selecting the right protein source poses its own set of challenges. Vegetable sources like soybean meal often require methionine supplementation due to their low levels of this amino acid. Animal-based sources are preferred due to their complete amino acid profile. For instance, hydrolyzed chicken protein, derived through enzymatic hydrolysis, is easily absorbed and provides bioactive peptides that offer additional nutritional benefits, such as enhancing palatability, providing antioxidant effects, and acting as immunostimulants.
Due to their role in growth, higher protein content is generally required during the early stages of a fish's life.
Lipids serve as energy sources and carriers of fat-soluble vitamins while also providing essential fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), crucial for fish development. These fats typically appear in proportions ranging from 5 to 30%.
Carbohydrates are another energy source, though they are inefficiently utilized by most species, particularly carnivores. Excess carbohydrates are stored as glycogen or fat. Carnivorous diets should ideally contain carbohydrates at a maximum of 20% for optimal animal utilization. Omnivorous species can tolerate higher levels.
Water-soluble and fat-soluble vitamins bolster the fish's immune system, and some act as antioxidants. Minerals regulate osmotic balance and support bone formation and integrity.
Production Time: Species-Specific Considerations
While the stages of fish farming are universal, each species exhibits unique characteristics throughout the process that farmers must understand. For example, tilapia, a popular freshwater fish, boasts rapid breeding times, typically ranging from 4 to 11 months, influenced by factors such as location, climate, temperature, water quality, and market demand.
Carp, requiring more delicate handling, has a longer average breeding time, around one year. Catfish also breeds in approximately one year, with its reproductive peak occurring within three years. Known for its predatory nature due to carnivorous eating habits, catfish possess voracious appetites, making it challenging for this species to refuse any offered food.
Conclusion
The stages of fish farming are clearly defined, each with its own set of characteristics that must be respected to achieve healthy development and optimized growth. Achieving this goal requires consideration of production timelines and meticulous attention to the fish's diet to ensure all necessary nutrients are included.
Preserved Strawberry,Candied Strawberry,Sweet Candied Strawberry,Preserved Dried Strawberries
Shanxi Fret International Trade Co.,Ltd , https://www.fretfruit.com