RAS technology

Some thoughts/observations on the current state of RAS technology as a viable alternative for aquaculture production

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By: Philip Buike*

I was asked recently: Why is it that relatively few large, established aquaculture production companies are involved in new RAS operations compared to the number of projects being promoted by operations with relatively little prior experience in the business?

Introductory Note

I would like to thank Mr. Salvador Meza for giving me a column in this prestigious and above all thought provoking publication. I feel both honored and privileged to be given the opportunity to contribute to Aquaculture Magazine, which has first published way back in 1968, must by now, be considered a leading reference for all things aquaculture related across the globe.

My mission will be to regularly provide articles that address current issues, particularly with respect to the wave of technological advances related to the move towards the inland production of both fish and shrimp.

RAS technology

First and foremost, my experience is in production, not sales, marketing, product placement or any other a host of related activities, and it is from this perspective that I will endeavor to provide objective information for both the prospective investor and seasoned operators alike.

With this in mind, my first contribution will be an in depth look to what extent RAS systems in general are currently or in the near future, could fulfill the high expectations associated with this relatively new production methodology.

Hopefully, we will be able to establish a FAQ and/or feedback space that will provide a forum for comments and suggestions for future topics. At the service of water people all around the World, Philip Buike, Independent aquaculture consultant.


I was asked recently: Why is it that relatively few large, established aquaculture production companies are involved in new RAS operations compared to the number of projects being promoted by operations with relatively little prior experience in the business?

If this is indeed the case, then probably because there are still number of knowledge gaps associated with RAS production in general, that have yet to be filled. With this in mind you, I have made a list of incognito, that personally require clarity if I were to invest in RAS production. Major questions that are still worth asking.

1.Can RAS be profitable?

In an efficient production system, feed should be the dominant cost, as the whole purpose of the exercise is to convert relatively low value inputs into high value proteins, values of around 60% of operating costs are the norm in pond-based fish production systems.

On the surface, RAS systems should be good as FCR´s are high due to highly controlled feeding systems, low feed loss, and theoretically at least, high survivals rates; but is this true in reality? because if not, this seriously depletes the validity of one of RAS´s major arguments, production efficiency.

“I think a well-designed, a correctly scaled RAS system should provide this 60% level of operating costs, but currently many operations are seeing their costs dominated by a combination of re-designing, labor, energy, and marketing costs.”

Energy costs are around 10% of total operating costs in those operations that do not require additional water heating (and have not specified how they deal with solid waste), this is manageable and not a reason in itself to drive the operation into negative profitability; however, those operations requiring additional water heating are in a very different position.

RAS technology

It appears, at least in Northern Europe, if the operation relies on commercial energy sources to heat their water, profitability becomes extremely elusive. The use of waste heat from other industrial operations via heat exchangers and/or the use of onsite renewables such as solar or biogas almost a prerequisite for a profitable operation.

“The capital cost of RAS systems is at least three times that of non-RAS equivalents with comparable production capacities, this figure rises further when the complete climate control is also required, as is the case with tropical shrimp culture in Northern Europe, for example.”

On top of this, RAS systems are very sensitive to operational scale, put simply, the bigger you go, everything will be cheaper. However, I think, on the whole, we are still some time away from the type of very large-scale investment is needed to demonstrate the true potential of RAS based production systems.

So, to answer this question, profitability it largely depends on what you are planning to produce (the more valuable per kilo, the better), the size of the operation, and the reliability of the design.

2.Will technical advances be sufficient to ensure long term operational reliability?

The first attempts at transferring salmon farming from sea to land have been littered with well documented, large scale fish kills, usually due to catastrophic system failures leading to major water quality deficiencies and/or major disease outbreaks.

At the end of the day, progressive degradation of culture conditions leading directly or indirectly to mortality continues to be a widespread problem, The argument is that with better filtration technology, suspended solids can be quickly and gently removed from the water column and all will be well.

Ok, my question is twofold, what about dissolved organic material? And what about the microbial population dynamics, particularly after sterilization procedures allow faster development, more competitive species to rapidly colonize the nutrient rich, decomposer poor post sterilization environment?

RAS technology

It is true to say that relatively passive techniques such as drum filtration do help, and novel approaches such as electrocoagulation may show benefit, but it appears that what the last ten years of RAS experience have really shown us, is that now we have a much clearer idea of the problems we face, but still no standard practice to provide a definitive, rock-solid solution to water quality management has become available.

In my opinion, therefore, for RAS to be a truly viable mainstream alternative to more conventional means of aquatic production, the concept needs to be proven repeatedly over a broad geographic area with a range of species and life stages.

3.Is RAS really that ecologically friendly?

The current criteria required to obtain the coveted “green label” for aquaculture derived produce is the following:

✓ Effluent treatment to allow safe return to the local environment.

✓ Habitat security.

✓ No harmful chemical use.

✓ Control and management of feed inputs.

✓ Prevention of escapees and maximum limitation of interaction between captive and wild stocks.

✓ High level of disease control.

✓ Certified non wild sources of seed.

✓ Maximum survival to harvest.

So, on these criteria alone, RAS would seem to fit the bill as far as “green” production systems go, however:

RAS aquaculture as currently practiced is both resource and energy intensive, and though not too much information is available, a figure of 8-10 kWh/kg of feed are reported as the norm for RAS salmonid production where no water heating was required (obviously, the energy cost of rearing a tropical organism like penaeid shrimp in Northern Europe will have a much higher energy requirement).

RAS technology

Interestingly, extensive phototrophic systems that have often been accused of being anti-ecological due to their large footprint per kilo of production has been almost insignificant energy costs, particularly in the case of tidally filled ponds.

So, it could be argued that while RAS does cover the basic tanning of “green” production, from a global point of view, it might not be very “green” at all.

4.Solid waste disposal

Before we go further into this issue, it is worth noting that solid waste production from aquaculture systems is in general very low in relative terms, be ing less than 5% of that generated in bovine meat production on a kilo for kilo basis.

RAS technology

However, solid waste from marine operations has a high salt con tent and needs considerable pretreat ment before it can be used as fertilizer for the land. This adds yet more capital costs and energy demand (usually in the form of reverse osmosis) to an already existing resource demanding form of protein production.

The possibilities of recycling waste via hydroponic vegetable production, polychaeta cultivation, and even a source of biomass for natural gas generation have been or are currently being considered, but to what extent these solutions can be broadly applied remains to be seen.

5.Land and water use

As the requirements for both of these valuable resources are low, RAS is normally considered to be good in this respect.

However, due to this very characteristic of frugal water requirements (relative to traditional land-based aquaculture systems), some potential conflicts with water use has surfaced in areas of critical water shortages; here is the question has become better use of a highly limited resource?

To maintain human life or to produce a luxury product for export. In certain specific circumstances, therefore, the application of RAS to allow aquaculture where previously there was none, could actually be detrimental to the needs of the local population.


Are RAS produced aquatic organisms as happy as their pond or cage dwelling counterparts? This is not a question I am equipped to answer, but given the higher stocking densities and the absolute dependence on artificial diets that are characteristic of RAS systems, you can be sure that sooner or later, someone will.


The purpose of this article is not to condemn RAS but rather to inject a dose of reality as a counterpoint to the current unbridled enthusiasm often seen on certain specialized platforms and publicity presentations.

Undoubtedly, RAS aquaculture has its place right now, and probably more so in the future, but that said, we need to be aware of its current limitations and where we can most benefit from the advantages of this type of production system can offer.

“There are currently examples of successful (profitable) RAS farms in operation that have correctly identified and maximized the plus points of this type of production system and worked very hard to minimize the negative aspects.”

For example, RAS technology had a very valuable role to play in the provision of shrimp larvae in new production zones.

RAS technology is appropriate in this case, as hatcheries in general, have to be highly controlled environments for them to work, their footprint, and water requirements are very small as low biomass is produced, but the value of the product is high, it is sold on tangible merits (not subject to the whims of a relatively unsophisticated market), and it is fundamental to the growth of an industry.

RAS technology

These are the very characteristics that are required to warrant the extra cost, complexity, and energy demand that are characteristic of RAS operations.

On the other hand, the application of RAS to produce a relatively low value species or life stages, especially if it is already being produced elsewhere on a very large scale at a comparatively low unit cost, is at present is justifiably questionable, even if all the “green” merits of this approach are in fact bona fide.

So, to get back to my first question: Can RAS be profitable? My answer would be, it all depends what you want to do with it?

Further reading

The University of Stirling in Scotland has published two excellent reports on the commercial reality of RAS technology (mainly in the context of Salmon farming) that are well worth reading if you have a specific interest in this area. (“Update on RAS technology” by J. Bostock et al 2019, University of Stirling, UK.).

Philip Buike

Philip Buike C.V. holds a bachelor’s degree in Fisheries Science from the University of Plymouth and a master’s degree in Aquaculture and Pathology from the University of Stirling.
He has over 30 years of industrial experience in shrimp farming and now has his own consultancy company specializing in intensive shrimp farming projects.
He built Europe’s only commercial shrimp hatchery in the Austrian Alps and is currently developing two new shrimp hatcheries in Northern Europe.

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