Amie Sarker

The South Asia Fisheries Research Project (SAFRP) ?n?sh production program was designed to explore the cost-eLective production of ?sh in a land-based facility using advanced technology. The project was designed to 1) maximize land and water use and use local materials and personnel to reduce costs and 2) simplify operating requirements to reduce training costs and enhance predictability and stability of outcomes over time.

The technology of choice was Bio?oc that can be loosely de?ned as managing two diLerent crops simultaneously in the same tank, ?sh and plankton. Bio?oc technology (BFT) eliminates the need for separate systems for nitri?cation, growout and degassing reducing the infrastructure complexity compared to Recirculating Aquaculture systems (RAS) and their inherent cost.

Methodology: BFT requires extensive mixing and aeration of the water to facilitate adequate oxygen levels and nitri?cation of ?sh waste products. The current SAFRP design requires tanks in order to optimize this water movement and eliminate issues normally related with pond sediment.

A group of 50-m3 tanks were stocked with sex reversed tilapia to evaluate land-based ?n?sh production using bio?oc technology. The tanks used aeration nozzles to simultaneously mix and aerate the water. The nozzles also facilitate eLicient self-cleaning and concentration of waste products in conjunction with a dual drain tank con?guration.

Nitri?cation was accomplished using bio?ocs in the water maintaining acceptable ammonia and nitrite levels throughout the growout period. The nitrate levels and total suspended solids (TSS) were controlled through limited water exchange and solids removal. The tank design includes an additional 3m3 sediment tank that receives 15% of the water ?ow from the main tank center drain. The waste produced is processed and composted and used as soil amendments.

BFT requires maintaining an adequate carbon/nitrogen (C/N) ratio in the water to eLiciently grow bio?ocs. This normally requires additional carbon, like rice ?our or molasses, to be added in addition to ?sh feed. The C/N ratio, size and age of the bio?ocs is controlled by managing the waste ?ow and carbon additions.

Results: After ten years of research and development, the SAFRP tanks are uniquely designed to eLiciently facilitate waste removal and minimize water losses while mixing and aerating the water. This includes the development of a patent-pending nozzle which reduces energy production costs signi?cantly.

A pond is usually limited to about 5000kg/ha, whereas the current operation of 60 tanks produces 10 times as much product in the same space and allows mixing of age and species cohorts during the production cycle. The larger tank base also allows the evaluation of a production scale BFT facility with a range of operational issues related to specie variation, production logistics, bio security, and water quality.

Annually, the SAFRP tanks produce 230,000 kg of ?sh. Fish quality has been signi?cantly enhanced with reduction of oL-?avors, and FCR has been decreased by 10-20% through the bio?oc technology. Additionally, the SAFRP hatchery produces 100 million ?ngerlings each year that supply both SAFRP’s own grow out tanks and are sold to local ?shermen for pond and other uses.

Audience take-away: 

• Bio?oc cultivation
• Infrastructure build/maintain
• Applying a unique design to ?n?sh production
• Nozzles
• Twin drains
• Tank advantages
• Bio security
• Production logistics
• Water management – Mature water/immature water/water exchange