In this article we will discuss about Polyculture:- 1. Meaning of Polyculture 2. Principle of Polyculture 3. Objectives 4. Origin 5. Drawbacks.
Meaning of Polyculture:
Polyculture or mixed fish farming or composite fish culture is the culture of fast growing compatible species of fishes of different feeding habits (or different weight classes of the same species) in the same pond so as to utilise the various available ecological niches in order to obtain high production per hactare of water body.
A pond according to its depth can be divided into three distinct zones — upper surface zone, middle column zone and bottom zone. A particular species exploits food of a particular zone. For example — Catla catla is a surface feeder, Labeo rohita a column feeder and Cirrhinus mrigala is a bottom feeder.
In case of single species or monospecies or monoculture only one zone will be utilised or exploited while the other zones would remain unutilised. As a result the entire ecological area would not be exploited and the yield or fish production would be less.
Principle of Polyculture:
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When different species of fast growing compatible fishes, occupying different ecological niches of a pond or any water body, are cultured together, they most efficiently utilises all the food sources available in the pond for fish production without harming each other.
Objectives of Polyculture:
(1) To obtain maximum yield or fish production.
(2) To utilise all the available niches.
(3) The fishes cultured should not cause any ecological disbalance.
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(4) The fish species cultured should not have any serious competition between them but each species may have a beneficial influence on growth and production of the other. For example, grass carp by consuming aquatic vegetation, converts plant tissue into fish flesh but its excreta fertilises the pond which benefits all other species.
(5) Some species of fishes are cultured which have specific roles to play in maintaining water quality in ponds by feeding on wastes accumulated in it. For example common carp and mrigal consume the faeces of grass carp and silver carp, which contain large amounts of undigested plant matter.
(6) Recent combination of fish species cultured are based on one or two spec