INTRODUCTION

Minimal exchange, intensive culture system requires little, if any, water exchange and has high animal stocking densities. In farm, water use in aquaculture can be up to 45 cubic meters per Kg produced in ponds. Within existing aquaculture pond system reduction in water use can be achieved through (1) selection of feed ingredients that needs little water, (2) enhancement if within system feed production, (3) integration of aquaculture with agriculture. Still these approaches will not make pond aquaculture more water efficient. This can only be attained through indoor fish farming systems like Recirculating aquaculture systems, aquaponics, biofloc technology (BFT) and other Zero water exchange aquaculture production systems.

Written By: Mayuri Nag1*, Govind Chaudhary2 and Priyanka Arya2
1,2 Govind Ballabh Pant University of Agriculture and Technology: Corresponding e-mail – mayurinag157@gmail.com

Recirculating aquaculture system

Recirculating aquaculture system is the most complex aquaculture system that rears fish at high densities in indoor tanks with a controlled environment. Recirculating system filters and cleans water for recycling back through fish culture tank. Since water is reused, the water volume requirement in RAS is only about 20% of what conventional open pond
culture demands. New water is added to the tanks only to make up for splash out and evaporation and for that used to flush out waste material. RAS conserves both land and water. RAS includes a series of treatment process- (1) Biofiltration (2) Solid removal (3) Oxygenation (4) pH control (5) temperature control (6) Biosecurity. The biological filter (biofilter) is the heart of RAS. It is a living filter composed of a media upon which a film of bacteria grows which provide waste treatment by removing pollutants. The two primary water pollutants that needs to be removed are – (1) Fish waste (toxic ammonium compound) (2) uneaten fish feed particles. The super intensive farming system though being high cost associated use as little as 300 litres of new water and sometime even less per kilo of fish produced per year, while intensive farming system requires 1000 litres of water per
Kg per year. The limited use of water makes it much easier and cheaper to remove the nutrients excreted from fish.

Aquaponics

Aquaponics refers to the system that combines conventional aquaculture with hydroponics in a symbiotic environment in which the waste produced by the farmed fishes or other aquatic creatures supplies the nutrients for plants grown hydroponically which in turn purify the water. It uses less than 10% of water normally required for fish farming and plant production and is considered – a short fish – based solution to growing food using limited resources and little water. From business perspective, system can be located almost anywhere, reducing system cost and lowering the carbon footprint of the enterprise. The bacteria are fundamental to this process. They convert ammonia (from fish waste nitrate, preventing the fish from becoming toxic. Most common being Tilapia that grows faster and can tolerate poor water quality. Plants like tomato, cucumber, lettuce and other green leafy vegetables can be grown in association.

Biofloc

Biofloc is another sustainable and ecoaquaculture through balancing carbon and nitrogen in the system. Bioflocs are aggregate of algae, bacteria, protozoan and other kind of particulate organism. This technique has recently gained attention to solve problems of water pollution and recycle nutrients found in water by a community of heterotrophic bacteria. Fish
(300g of biomass per square meter) with conventional water treatment technology used in aquaculture. Biofloc technology is robust, economical technique, easy in operation (decrease of water treatment order of 30%) which makes it possible to minimize water exchange and water usage,
providing low cost bioflocs rich in protein.

Conclusion

Aquaculture has been growing faster due to the demand of products world over. This rapid growth of aquaculture has created serious threat for water and land, degradation. Application of Zero Water Exchange Aquaculture Production system is a viable alternative to traditional pond methods. It is expected to yield increasing economical efficiency and sustainability. Multitrophic Recirculating Aquaculture System (MARS) assures
future success of aquaculture and sustainable indoor fish farming is the farming of the new millennium to this process. They convert ammonia (from fish waste trate, preventing the fish from becoming toxic. Aquaponics is suitable for several fishes most common being Tilapia that grows faster and can tolerate poor water quality. Plants cumber, lettuce and other green leafy vegetables can be grown.

Biofloc is another sustainable and eco-friendly technique of enhancing water quality in aquaculture through balancing carbon and nitrogen in the system. Bioflocs are aggregate of algae, bacteria, protozoan and other kind of particulate organism. This technique has recently gained attention to solve problems of water pollution and recycle nutrients found in water by a community of heterotrophic bacteria. Fish are grown intensively (300g of biomass per square meter) with zero or minimum water exchange. Compared to conventional water treatment technology used in aquaculture, Biofloc technology is robust, economical technique, easy in operation (decrease of water treatment expenses in the order of 30%) which makes it possible to minimize water exchange and water usage, providing low cost bioflocs rich in protein.

Aquaculture has been growing faster due to the demand of products world over. This rapid development has created serious threat for water and land degradation. Application of Zero Water Exchange Aquaculture Production system is a viable alternative to traditional pond methods. It is expected to yield increasing economical ability. Multitrophic Recirculating Aquaculture System (MARS) assures future success of aquaculture and help to guarantee the security of environment. Hence, sustainable indoor fish farming is the farming of the new millennium.

Written by: Mayuri Nag1*, Govind Chaudhary2 and Priyanka Arya2
1,2 Govind Ballabh Pant University of Agriculture and Technology: Corresponding e-mail – mayurinag157@gmail.com