MP Board · Class 9 · Science · Improvement in Food ResourcesExplain the concept of Composite Fish Culture System in detail by addressing the following key aspects: Define Composite Fish Culture and state the underlying principle of using multiple fish species in a single pond. Name five distinct fish species commonly reared together in this system, specifying the exact feeding zone (niche) of each species within the pond environment. State three major advantages of practicing Composite Fish Culture. Identify the primary operational problem/limitation associated with composite fish culture and explain how modern aquaculture overcomes this issue.

Composite Fish Culture System

1. Definition and Principle\nComposite Fish Culture is an intensive fish farming system in which five or six different compatible fish species (a combination of local and imported species) are reared together in a single fish pond.

Underlying Principle: The selected species have different feeding habits and occupy different ecological niches (feeding zones) within the pond water column. Because their food requirements do not overlap, they do not compete with one another for food. This ensures that all available natural food resources across all depth levels of the pond are efficiently utilized, resulting in maximum total fish yield per unit pond area.

2. Species Used and Their Feeding Zones\nIn a typical composite fish culture system, six fish species are categorized based on their specific feeding zones:

• Surface Feeders:
  • Catla (Indigenous): Feeds on zooplankton and organic matter present on the water surface.
  • Silver Carp (Exotic): Feeds on phytoplankton available in the surface layer.
• Middle-Zone Feeders (Column Feeders):
  • Rohu (Indigenous): Feeds on plant matter and algae in the middle depth of the pond water.
• Bottom Feeders:
  • Mrigal (Indigenous): Feeds on decaying organic matter and detritus present at the pond bottom.
  • Common Carp (Exotic): Feeds on bottom vegetation and micro-fauna at the pond floor.
• Vegetation / Weed Feeders:
  • Grass Carp (Exotic): Feeds on macro-vegetation and weeds growing in the pond.

3. Advantages of Composite Fish Culture

• Maximum Resource Utilization: Food present in every layer (surface, middle, and bottom) of the pond is completely consumed without waste.
• High Production Yield: Yield per hectare is significantly higher compared to monoculture (rearing a single species).
• Zero Food Competition: Since each species occupies a distinct ecological niche, inter-species competition for food is virtually eliminated.

4. Major Problem and its Solution

• Primary Problem: A major limitation of composite fish culture is the lack of availability of high-quality fish seed (spawn/eggs). Most of these commercial fish species breed only during the monsoon season. Even if seeds are collected from wild riverine sources, they get mixed with undesirable species, leading to high mortality and low purity.
• Modern Solution (Hormonal Stimulation / Induced Breeding): To solve this issue, fish farmers now practice induced breeding using hormonal injections (such as pituitary gland extracts or synthetic hormones). This technique stimulates the adult fish to spawn under controlled hatchery conditions at any required time, ensuring a reliable supply of pure, high-quality fish seed.