Recirculating Aquaculture Systems. The Good, the Bad and the Ugly

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By: Yedod Snir


RAS provides us with an alternative to ponds, cages and wild catch. In RAS we grow Seafood on land, with minimum resources and isolated from the Environment. The growing demand for seafood and protein to feed the billions of people on earth and the scarcity of natural resources, has made the development of RAS a necessity, not a choice.

Despite the steep learning curve of RAS, many companies are invested in large projects to offset the high investment required per production unit capacity (Economy of scale) This magnified risk is not necessary with the right technologies and design. With regards to the cost of production, growing fish in RAS which is designed and operated correctly, can be cost-competitive.


Small footprint – with avg. densities at approx. 4-5 x cages and 40 x ponds, RAS is compact, allowing its convenient deployment in population centers.

Controlled conditions – Temps, Salinity, Photoperiod are some of the most critical drivers of the major physiological processes.

Reduced labour – A smart Ergonomic design will achieve significant cost saving through mechanization and automation.

Market advantage – Potential for a fresh locally produced wholesome product that can hit the markets daily with consistent quality and a competitive price (Freight savings).

Ecological – Primary oxidation of Nitrogen (No3) and Carbon (Co2), or with further efforts completion of C&N cycle through degassing or N&P via crop root uptake.

Biosecurity – A land-based Ecosystem that reduces the propagation of common pathogens such as Sea lice and/or Bacterial and Viral agents.


Small footprint – High fish densities demand efficient oxygen dissolving systems which require complex gas fundamentals understanding and management.

Controlled conditions – Many parameters cannot be measured practically inline or controlled and the greater Recirculation to control those parameters conversely decreases control.

Reduced labour – A smaller staff requires retaining a carefully selected “A team” of dedicated professionals with a deep understanding of the system.

Market proximity – The Carbon footprint is not necessarily lower than other culture systems, contingent on, location, RAS design, and operations.

Ecological – In absence of Denitrification or Crop Nutrient assimilation, RAS basically converts Organic to Inorganic Nitrogen and increases Phosphate.

Biosecurity – Poor water or feed quality in RAS may create novel pathogens which are unique to the system and do not respond to generic treatments developed and applicable to vast regions of culture.


Capital investment – RAS is capital intensive and is set for unexpected maintenance and depreciation costs if built wrong. The real ROI for most RAS systems is still very low.

Operating expenditure – A poorly executed design exacerbated by a poor operation will increase OPEX to a point where the Economy of scale is considered as a strategy for the wrong reasons.

The Environment – RAS started as an environmentally friendly concept to save water and reduce impacts. Today in many parts of the world, water scarcity and partial nutrient cycles are simply not technically or economically sustainable.

The Image – Crowded culture conditions gives RAS a bad image as if the fish are “swimming in their own waste”. It doesn’t help to have projects that have rusty corrosive buildings.


The RAS Paradox: “Everything is under “Control!”

The term “Technology” is being tossed around for marketing purposes these days to confer a sense of mechanical predictability, but the economic success of an Intensive RAS company is more dependent on people than any other standalone factor! Every single link of the Value Chain is critical, and this goes on 24/7. Monitoring and even control Technology is advancing and supports RAS redundancy, however, adds to the complexity so must be used strategically.

References cited by the author available under previous request to our editorial team. Tel: +1 413 7689300 E-Mail:

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