On the basis of intensity of input and stocking density aquaculture is categorised as follows.
- Extensive fish farming system
- Semi-intensive fish farming system
- Intensive fish farming system and
- Integrated aquaculture system
Extensive fish farming system
The extensive fish farming system is the least managed form of fish farming, in which little care is taken. This system involves large ponds measuring 1 to 5 ha in area with stocking density limited to only less than 5000 fishes/ha. No supplemental feeding or fertilisation is provided. Fish depends only on natural foods. Yield is poor (500 to 2 ton/ha), and survival is low. The labour and investment costs are low, and this system results in minimum income.
Semi-intensive fish farming system
Semi-intensive fish culture system is more prevalent and involves rather small ponds (0.5 to 1 hectare in an area) with higher stocking density (10000 to 15000 fish/ha). In this system, care is taken to develop natural foods by fertilisation with/without supplemental feeding. However, the major food source is natural food. Yield is moderate (3 to 10 ton/ha), and survival is high.
Intensive fish farming system
An intensive fish farming system is the well-managed form of fish farming, in which all attempts are made to achieve maximum production of fish from a minimum quantity of water. This system involves small ponds/tanks/raceways with very high stocking density (10-50 fish/m3 of water). Fish are fed wholly formulated feed. Proper management is undertaken to control water quality by use of aerators and nutrition by use of highly nutritious feed. The yield obtained ranges from 15 to 100 ton/ha or more. Although the cost of investment is high, the return from the yield of fish exceeds to ensure the profit.
Integrated aquaculture system
Fish farming with agriculture
In the fish integrated agriculture system, fish culture is integrated with agricultural crops such as rice, banana and coconut, thereby producing fish and agricultural crops. Agriculture based integrated systems include rice-fish integration, horticulture-fish system, mushroom-fish system, Seri-fish system.
- Rice-Fish integrated farming - In this system of farming, fish is farmed in paddy fields, not all paddy varieties are suitable for integrated fish farming. Varieties with the strong root system like Tulsi, Panidhan, CR 260 77, ADT 6, ADT7, Rajarajan and Pattambi 15 and 16 are suitable for farming in combination with fish because it has strong roots to withstand flood conditions. The fish species such as Common carp, Tilapia and Murrells are most suitable for culture in rice fields.
- Horticulture-Fish integrated farming - The dykes and the adjoining areas of the ponds can be best utilized for horticulture crops. The top, inner and the outer dykes can be planted with dwarf variety coconut, mango and banana. And the side by land can be used for planting pineapple, ginger, and turmeric and chilly. The exchanging water can be used to water the plants which are rich in organic load. The residues from the vegetables cultivated could be recycled into fishponds, mainly when stocked with fishes like grass carp.
- Mushroom-Fish integrated farming - Cultivation of mushroom requires a high degree of humidity and therefore its cultivation along with tremendous aquaculture scope. Agaricus bisporus, Voloriella spp. and Pleurotus spp., are commercially cultured mushrooms in India.
- Seri-Fish integrated farming - In this farming system, silk worm is cultured along with fish. Here the mulberry leaves produced is primarily consumed by the silkworm and the faeces of the silkworm are directly applied to the fish pond to increase of natural food organism-detritus and bacteria in the fishpond.
Livestock integrated fish farming
Livestock integrated fish farming system includes the cattle-fish system, pig-fish system, poultry-fish system, duck-fish system, goat-fish system, rabbit-fish system. In this integrated farming the excreta of ducks, chicks, pigs and cattle are used directly in ponds to increase plankton production which is consumed by fish or serve as direct food for fish. Hence, the expenditure towards chemical fertilisers and supplementary feeds for fish ponds are totally avoided reducing the production cost.
- Pig-Fish integrated farming - In this farming system, 60-100 no of pigs are enough to fertilise one-hectare area fish pond. A floor space of 3-4m2 is required for a single pig. Five tons of pig manure is necessary for manuring 1 ha fish pond for 1 year. Pigs are fed with kitchen waste, aquatic plants and crop wastes. The waste produced by 30-35 pigs is equivalent to 1 tonne of ammonium sulphate. Exotic breeds like White Yorkshire, Landrace and Hampshire, are reared in this farming system. Grass carp, silver carp and common carp (1:2:1 ratio) are suitable for integrated farming with pigs.
- Poultry-Fish integrated farming - Chicken droppings are rich in phosphorus and nitrogen, so chicken manure is an effective fertiliser. For 1ha fish pond 25,000 chicks can be reared. Poultry shed is constructed above the pond with bamboo flooring to facilitate the direct fertilization of the pond. One chicken produces 25 kg poultry manure per year. From poultry 90,000 to 1,00,000 eggs and 2500 kg meat can be produced and 3000 – 4500 kg of fish can be produced without any chemical fertilizer and supplementary feeding.
- Duck-Fish integrated farming - In Duck-fish integrated farming, ducks provide a safe environment to fish by consuming juvenile frogs, tadpoles and dragonfly in the pond. As the duck spends most of its time swimming in the pond the dropping goes directly in pond, which in turn provides essential nutrients to stimulate the growth of natural food in the fish pond. The duck dropping contains 25 percent organic and 20 percent inorganic substances with some elements such as carbon, phosphorus, potassium, nitrogen, calcium, etc. Hence, it forms an excellent source of fertiliser. To fertilise 1 ha fish pond number of ducks required is between 100 and 3,000, depending on the duration of fish culture and the manure requirements.
- Small ruminants such as goats and sheep are integrated with fish culture is practiced but on a very small scale. Integrated rabbit-fish farming is also practiced only on a tiny scale. This system has up to now not received much attention.
- Pillay, T. V. R. and Kutty, M. N. 2005. Aquaculture: Principles and Practices. Blackwell Publisher
- Principle of aquaculture. Online e-course of ICAR.