Fish farming can be new industry in inland districts

Anne Berit Bjørken

"Until now, the fear of disease transfer to wild fish populations, has put strict limits on fish-farming in inland areas of Norway. We believe that we have developed a relatively simple technology that will mean that fish farming can take place without any danger of harmful discharges of nutrients and fish pathogens, which ought to make it easier to obtain permission to start small-scale farming of freshwater fish in rural districts. We believe that this technology could be the basis of a supplementary income for farmers threatened by competition but with access to water resources," says head of research, Dr. Bjørnar Eikebrokk of SINTEF NHL, who has been at the centre of the development of the BIOFISH simplified recirculation tank.

The BIOFISH tank is already in commercial production, and the investment needed is not great. The tank is a closed aquaculture system suitable for charr, salmon, trout etc., as well as for raising fry and fish for stocking. It is fitted with its own simple biological water treatment unit which means that water consumption is extremely low, since the water is used over and over again. Air is blown into the water to ensure that the oxygen supply is adequate. Pure oxygen can also be used. The freshwater consumption of a 7 m3 BIOFISH tank applied for the production of brown trout restocking fish, is only 7 - 10 litres a minute, compared to a consumption in a typical flow-through system, which is as high as 150 - 200 litres a minute. The low water consumption and the integrated biological water treatment system make it simple and cheap to disinfect the water against any disease-carrying microorganisms. The tanks that have been tested are three metres in diameter and about a metre deep. The results of a three-year demonstration and test project at A.L. Settefisk, where the fish farmer used and operated the system himself, have been very good. The self-cleansing unit functions extremely well, feed consumption and discharges are low, and the fish have grown well. The BIOFISH tanks have also turned out to be very simple to operate.

The BIOFISH system has also been tested in Trondheim and in a number of other places in Norway. The University of Trondheim, AVH has purchased the system for its research station. In order to demonstrate the system and document its efficiency and reliability and to develope the system even further, SINTEF, the Veterinary Medicine Centre for Aquaculture Research and the Bandaksmolt company have applied to the Ministry of Agriculture for support