Aquaculture's hope for bright future for rural people

Adita Sharma¹ and Dr.Amita Saxena²

India's annual fish production is 144.2 million tonnes and share of aquaculture is only 53.2 million tonnes & capture fisheries 91.0 million tonnes. The annual per capita fish consumption of our country is 9 kg. The advisory committee on human nutrition has on the other hand recommended 31 kg. This shows that the demand for fish outstrips supply and aquaculture is considered to be the only alternative to capture fisheries for producing more protein to combat malnutrition.

Aquaculture, the culture of the commercially important animals, is a dependable year round source of animal protein unlike agriculture or animal husbandry. Further, it is a more profitable venture than maintaining live stock as the food conversion ratio in fish is better than pig, chick or cattle. Aquaculture currently provides 10% of world's water derived protein and about 3% of all worlds' protein exclusive of milk.

Freshwater aquaculture: Though freshwater bodies of India amount to 7.5 million ha, we at present use only 1.7 million ha of reservoirs and lakes and 0.15 million ha of ponds for an annual aquaculture yield of 0.14 million tones. Hence more freshwater bodies have to be brought under aquaculture using the following practices:

Composite fish culture: Fast growing compatible carps with different feeding habits such as Catla, Rohu, Mrigal, Silver carp, Grass carp and Common carp can be stocked together in earthen ponds and get a yield of more than 10 t/ha.

Air breathing fish culture: Derelict shallow waters with poor oxygen content could be utilized for culturing air breathing fishes such as Magur, Singhi and Murrels. In India, about 1.24 million hectare of swampy areas is available for this practice.

Sewage- fed fish culture: Sewage waters can be treated in oxidation ponds and subsequently used for fish culture. This technology can be availed of in big cities like Mumbai, Chennai, Bangalore, etc. where part of sewage is now drained into adjoining wet lands. These wet lands can be used for sewage fed fish culture. As there is no expenditure towards fertilizer and feed, this is a very lucrative venture and a yield of 10-14 t/ha/yr is possible besides making the environment clean.

Integrated fish farming: Fish can be cultured along with agricultural crops such as rice and banana and live stock such as poultry, duck, cattle and pig. While rice and banana fields give space for fish culture, live stock excreta is either recycled or serve as direct food for fish. The pig cum fish culture and duck cum fish culture have given and yield of 8000kg/ha and 5000kg/ha respectively. Pig cum fish culture can also benefit tribal population in north eastern hill states where pigs are traditionally reared. Similarly, duck cum fish culture can be practiced in Tamil Nadu, Kerala, Assam, Orissa, West Bengal and Bihar where duck rearing is common.

Fish culture in rice field: Fish like carp, murrels and tilapia can be cultivated simultaneously or in rotation in the trenches adjoining rice fields which offer additional revenue to the agriculturists. It is possible to get a fish yield of 700 kg/ha during the paddy cultivation season. Through an area of 6 million ha is under rice cultivation in India, only 0.03% of this is now used at present for rice fish culture. Hence, there is good scope for implementing this venture as an agro based industry especially in the rainfed low lying areas covering an estimated area of 2 million ha in West Bengal, Assam, Tripura, Orissa, Bihar and U.P.

Larvivorous fish culture: Larvicidal fishes such as Oryzias melasigma, Aplocheilus blochi and Gambusia affinis can be cultivated in cement cisterns and their mass production can control malaria, filarial, dengue and brain fever which affect humans through vectors like mosquitoes.

Ornamental fish culture: As aquarium fishes have a good export market in Singapore, Malaysia, UK and USA the culture and proliferation of these fishes through indoor breeding is a profitable venture.

Brackish water aquaculture: Our country is blessed with 1.7 million ha of brackishwater bodies such as estuaries, backwaters and mangrove waterways. The brackishwater areas such as Pokkali fields of Kerala (5117ha), Bheries of West Bengal(2000 ha), Gazani farms of Karnataka and Khazan lands of Goa have been found more suitable for undertaking the traditional fish and prawn culture practice viz. trapping and filtration. However, large scale farming of prawns is practiced only in the brackishwaters of west Bengal, kerala, Karnataka and Gujarat, covering an area of about 30,000 ha and the present annual yield is about 10,000 tonnes. As brackishwater areas of our country are abundant with over 26 species of commercially important fishes, prawns, carbs and mollusks, they offer vast scope for cultivating fish and prawns. Prawn farming among others is certainly a lucrative venture as it gives an annual producing of 2.1 t/ha through three crops. It is also worth mentioning that if the remaining unutilized brackishwater areas brought under prawn farming, it is possible to produce annually 0.1 million tones of prawn which can give a return of about Rs. 500 crores. As prawns are our major item of exports among seafoods (90%) prawn farming especially in brackishwater ponds would not only enhance the national income but create employment opportunities.