Question:
In rivers & lakes fish poop and urine are washed away: what happens in concrete, tarpaulin or less flowing pond?
Recirculating aquaculture system is essentially a technology for farming fish or other aquatic organisms by cleaning and reusing the water in the production.
The technology is based on the use of *mechanical* and *biological filters*, *UV light* and the method in principle can be used for any specie of aquatic animal such as tilapia, catfish, lobsters, shrimps, etc
RAS is growing rapidly in many areas of the fish farming industry. DelTin and Joana Farms use it extensively on our farm.
Systems are deployed in production units that vary from huge plants generating many tons of fish per year for consumption to small sophisticated systems used for restocking or to save endangered species
Recirculation can be carried out at different intensities depending on how much water is recirculated or re-used.
Some farms have super intensive farming systems installed inside a closed insulated building using as little new water per kilo of fish produced per year
Other systems are traditional outdoor farms that have been rebuilt into recirculated systems using more new water per kilo of fish produced per year
Seen from an environmental point of view, the limited amount of water used in recirculation is of course beneficial as water has become a limited resource in many locations.
Traditional fish farming is totally dependent on external conditions such as the water temperature of the river, cleanliness of the water, oxygen levels, or weed and leaves drifting downstream and blocking the inlet screens and cages, etc.
In a recirculated system these external factors are eliminated either completely or partly, depending on the degree of recirculation and the construction of the fish farm
Recirculation enables the fish farmer to completely control all the parameters in the production, and the skills of the farmer to operate the recirculation system itself becomes just as important as his ability to take care of the fish.
Controlling parameters such as water temperature, oxygen levels, or daylight for that matter, gives stable and optimal conditions for the fish, which again gives less stress and better growth.
These stable conditions result in a steady and foreseeable growth pattern that enables the farmer to precisely predict when the fish will have reached a certain stage or size.
The major advantage of this feature is that a precise production plan can be drawn up and that the exact time the fish will be ready for sale can be predicted. This favours the overall management of the farm and strengthens the ability to market the fish in a competitive way.
By Dela Benson Bani (CEO, DelTin Ventures)