The correct option is A-2, B-3, C-4, D-1
Explanation
The Composite Fish Culture (Polyculture), a technique in aquaculture where multiple fish species are reared together in a single pond. These species are selected based on their distinct feeding habits and preferred water depths (ecological niches) to ensure that all available food resources in the pond are utilized without competition.
Detailed Analysis:
- A. Catla (Catla catla): It is a surface feeder. It occupies the upper layer of the water column and feeds primarily on zooplankton and phytoplankton. (Matches with 2)
- B. Rohu (Labeo rohita): It is a middle-zone feeder (column feeder). It occupies the middle layer of the pond and feeds on filamentous algae and decaying vegetation. (Matches with 3)
- C. Mrigal (Cirrhinus mrigala): It is a bottom feeder. It inhabits the bottom zone and feeds on decaying plants, detritus, and organic matter. (Matches with 4)
- D. Grass Carp (Ctenopharyngodon idella): It is a weed feeder. It consumes aquatic weeds and macro-vegetation, often serving a dual purpose of food production and biological weed control. (Matches with 1)
Conclusion:
The correct matching sequence is A-2, B-3, C-4, D-1.
Key Takeaway:
In composite fish culture, species stratification maximizes productivity: Catla feeds on the surface, Rohu in the middle zone, Mrigal at the bottom, and Grass Carp consumes aquatic weeds.