The Mid-Norwegian Ring (MNR) improves the water environment in cages by transporting water upwards.

How it works

  1. Pressurized air is transported to an aerator in the lower part of the cage.
  2. Bubbles is distibuted in an aerator.
  3. The bubbles drag water upwards.
  4. The water in the cage is exchanged.


You can read more about SalMar and Midt-Norsk havbruk’s experiences on

NorseAqua supplies ready to use solutions


MNRSystemtegning 1

Major components:

  • Compressors
  • Flowcontrol module
  • Aerators
  • Piping.


Mythbusters demonstrates the concept

The solution is continously improved in collaboration with our customers.


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Possible positive gill health effect

Gills are delicate structures easily affected by poor water quality and accumulation of particles in the water. Water environment has great significance for gill health in both salmon and cleaner fish residing in the upper water column. So far observations indicate that the pressure the MNR generates from the center of the pens, is contributing to keep particles from accumulating inside the skirt area.


Additional prevention of Sea Lice infestation

Air bubbles transport fresh water from the depths and improve the aquatic environment in the upper water layers. This allows us to keep the skirts on during periods where critical oxygen conditions normally would force us to remove or raise the skirts, and thereby risking sea lice infestation.

Effects in situations with low oxygen

We observe that the fish periodically pull into the air column, especially on sites where oxygen levels are low. Early results indicate that the oxygen levels in the cage are improved considerably in low oxygen conditions.

Patent pending and licencing

Midt Norsk Havbruk (MNH) is committed to contributing to the development of innovative solutions that lead to sustainable growth. The method associated with the Mid-Norwegian ring (MNR) is under patenting.

  • Each company that want access to the method is therefor asked to sign a confidentiality agreement.
  • MNH have established a fund for future investment in new technology or new companies, for the development of aquaculture. To use the MNR method, MNH would like each company to contribute to the fund.
  • If you wish to use the ring on one or more of your locations, a fee of 10 000 NOK ( is incurred per. license. The fee will be added to the fund administered by Midt Norsk Havbruk (MNH).

NorseAqua – a preferred partner and supplier of MNR

Norse Aqua is proud to have gained the trust and confidence to develop the solution further. The Mid-Norwegian Ring fits well with our vision, expertise and innovation drive. Norse Aqua has unique access to empirical data, giving us the following advantages:

  • Optimal design of components.
  • Overall operating experience from different regions.
  • Knowledge of utilization in commercial operation.

In order to deliver the best solution, we work towards continuous improvement.

Please contact us if you have questions about how to proceed in order to obtain the Mid Norwegian Ring and how it is used! We help you with everything you need to know!

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