Aquaculture Principles and Fertilizers

Culture Systems and Methods in Aquaculture

• Culture Relative to Natural Food:

  • Lablab method.
  • Lumut method: Fish reared with filamentous grass green algae as primary food; may include supplemental feeds.
  • Lumut: Filamentous grass green algae growing from the pond bottom to the surface.

• Types of Lumut:

  • Chaetomorpha linum: Unbranched filamentous green alga (Lumutjusi).
  • Cladophora: Branched filamentous green alga.
  • Ulva intestinalis/tubulosa: Alga resembling young noodles, and fowl intestine in adult stage.

Methods of Culture Relative to Fish Sex

• Monosex Culture: Involves rearing either female or male fish exclusively to limit reproduction.
  • Mostly applicable to tilapia.
• Advantages:
  • Improved growth rates due to faster-growing sex leading to enhanced productivity and efficiency.

Principles of Aquaculture

• Commercial Inorganic Fertilizers:

  • Common types: Urea (46-0-0), Ammonium sulfate (21-0-0), Triple superphosphate (0-46-0), and more.

• Efficient Fertilization:

  • More effective during sunny days due to increased photosynthesis and nutrient uptake; less effective in rainy or overcast conditions.
  • Higher temperatures enhance microbial activity aiding fertilizer absorption.

• Fertilization Risks:

  • Rain can wash away fertilizers and reduce effectiveness.

• Species Growth Potential:

  • Fish species with larger maximum sizes typically grow faster during their juvenile stages.

• Diversity in Feeding:

  • Raising different species with varying food habits leads to better resource utilization and biomass accumulation.

• Increasing Carrying Capacity:

  • Additional feeds (supplemental or complete) can support higher fish populations.
  • Supplemental feeding enhances natural food availability, while complete feeding replaces the natural diet.

• Feeding Strategies:

  • Maintenance feeding is non-economical as it does not promote growth.
  • Overfeeding leads to waste and unnecessary costs.

• Yield Considerations:

  • Maximum yield is limited by the carrying capacity of water in aquaculture systems.
  • Higher fish density increases the risk of diseases and parasites.

Types of Culture Systems

• Pond Culture: Utilized for species such as milkfish, shrimp, seabass, etc.
• Cage/Pen Culture: Suitable for various fish, including tilapia and snapper.
• Raceway Culture: Commonly used for species such as milkfish and grouper.
• Recirculating Aquaculture Systems: Employed for tilapia, trout, and shrimp.
• Raft Culture: Specifically for shellfish like mussels and oysters.

Monoculture vs. Polyculture

• Monoculture Advantages:

  • Higher yield due to optimal environmental conditions tailored for a single species.
  • Simplified management and reduced risk of disease transmission.
  • Potentially higher profits by responding to specific market demands.

• Monoculture Disadvantages:

  • Increased disease risk, environmental degradation, and genetic homogeneity.
  • Vulnerability to market fluctuations and changes in consumer preferences.