Aquaculture Blog - Let's Talk!

Oxygen Starvation

BY Leslie Ter Morshuizen

The technical term for low oxygen concentration in water, which finally leads to fish mortalities, is hypoxia.  This is the condition where the oxygen dissolved in the water is inadequate for the fish to be able to breathe normally, resulting in stress and ultimately death.  Different species vary enormously in their ability to take up oxygen from water, and also in their tolerance of such low levels, and even within a species the smaller fish tend to be more efficient oxygen harvesters than larger fish.
 
The environment of an earth pond is generally based on culturing algae to stimulate the food web, providing natural feed and thereby reducing the feeding costs of the fish.  Algae photosynthesise by day, giving off abundant oxygen into the water to the delight of the fish and other organisms in the pond.  Unfortunately, the algae cannot photosynthesise at night and rather switch to respiration, competing with the fish and other aerobic organisms for oxygen.  Under nocturnal conditions the oxygen levels in a pond therefore plummet, requiring the use of manual aeration to avoid the dissolved oxygen levels from dropping too low to sustain the fish.  This situation is aggravated by several consecutive days of cloudy weather, which reduces photosynthetic oxygen production by day, causing the night time concentrations to fall even lower.  Yet another compounding factor is water temperature in that warm water holds less oxygen at saturation than colder water, so summer waters are naturally lower in oxygen than the same system in winter.  Cruelly, the metabolism of our fish is higher in warm than cool water, further increasing the demand for this critical element that is in short supply under these conditions.
 
In recirculating systems the fish are stocked at high densities and oxygen levels are sustained by means of water flow and aeration or oxygenation.  Should these mechanical methods of life-support stop functioning the fish will quickly become stressed and display symptoms associated with hypoxia.
 
When the concentration of dissolved oxygen falls below the level required by the fish for comfort they will typically respond in predictable ways, displaying visible symptoms including gasping at the surface, congregating at the water inlet, piping (sucking in surface water) and rapid, exaggerated gill movements.  If the situation is not corrected they ultimately they tend to die with their gills flared and mouths wide open.
 
In ponds, cages or recirculating systems, the amount of oxygen in the water will be reduced if the fish are stocked at a density that is too high for that environment or if the culture tank has high levels of suspended organic particles.  These particles are colonised by bacteria and other microorganisms which require oxygen as they breakdown these tiny specks, thereby reducing the amount of oxygen available for the fish.  For most fish species the minimum level that fish are happy with is around 5mg/?.  At this oxygen concentration the fish can digest their feed efficiently and grow well.
 
It is therefore important to observe a few basic rules in order to prevent hypoxia occurring in our culture tanks.  These rules are simple and include the following:

  • never overstock the environment
  • avoid the temperature increasing to levels that exceed the optimal for the species and the design of the system
  • keep the amount of organic material in the water as low as is practical
  • ensure there is adequate aeration to maintain the required dissolved oxygen levels.
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 December 05, 2016
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Can Aquaculture make a difference

BY Leslie Ter Morshuizen

A brief trawl on the internet quickly shows that a large number of people across the continent are desperately poor and in need of both food and work.  Plough a little deeper and you realise that urban migration, deforestation and water shortages are also becoming headaches for African governments.  Following on the 2011 census in South Africa, unemployment and urban migration were listed as two of the greatest challenges facing the Country.
 
Aquaculture has the ability to directly address these issues.  As an intense form of agriculture, limited land and very little water are required to raise fish.  Cage culture and recirculating systems essentially do not consume any water but rather borrow it for a period of time.  Earth ponds do result in some loss through evaporation and seepage, but this too is limited.  Aquaculture is also best conducted in areas where land prices are not too high, which is typically the rural spots where you want to employ people to decrease the urban migration trend.  The final advantage relates to the many health benefits associated with eating fish and other forms of seafood.
 
So Aquaculture clearly does have enormous potential to make a difference in the lives of the rural poor in Africa, and elsewhere across the globe.  However, this Industry is skills intensive, meaning that it is best suited to being conducted via the Hub & Spoke or Satellite Grower model.  The key technical expertise, equipment, feed and seed stock are supplied to associated Growers from the Core, thus enabling people who lack the depth of skills to still participate in the Industry.  In this way large numbers of fish can be produced based on the skills of a limited number of key personal that perform the most complex and demanding tasks, whilst the bulk of the routine tasks are carried out by less skilled individuals.  In this manner Aquaculture can truly make a difference to a large number of people.

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 December 05, 2016
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Wake Up

BY Leslie Ter Morshuizen

Spend some time travelling through your country or our beloved continent and you will notice certain changes across the landscape.  Trees are being felled at an alarmingly rapid rate, and no, there is not a planting program to replace the disappearing forests.  Road networks are improving; whilst this is good for development it also provides the arterial network required by the logging companies to transport the timber stripped from the forests.  You will also notice that there are people almost everywhere, even in areas that 5 years ago were virtually uninhabited.  More people means more pressure on the local environment through bush clearing for crop farming, grazing of domestic stock that displaces wild animals, water being required for irrigation, stock and household use, and of course the wastes that area generated and often simply discarded as litter (country dependant!).
 
In much of Africa the citizens are actively engaged in one of three activities: fishing, farming or trading.  Fish stocks are mostly seriously depleted to the point that this is now a marginal enterprise.  This situation is easy to remedy – stop fishing until the stocks recover and then only harvest sustainable sizes and quantities; but history shows us that this is not going to happen.  In South Africa you generally do not see the levels of commercial activity, especially farming, that you see throughout the rest of Africa.  It is as if the security of a State grant has robbed people of their urgency and creativity to place food on the table, or perhaps this is merely an expression of a cultural difference?
 
When we read reports on the state of water resources across the continent we learn that there is grave concern over the rate at which water sources are being spoilt by inappropriate agricultural and mining practices, along with other forms of industrial and urban pollution.  Water is a most precious commodity and the writers stress that urgent attention is required to avoid a significant number of catchments becoming polluted to the point of being unsuitable for use!  Many methods are available to reduce aspects of our negative impacts on water sources, but do we have the collective will to change our behaviour?
 
The IMF is warning of a global financial crunch starting in 2016/7.  Have read around the subject a bit there seems to be strong agreement across much of the financial media that a financial downturn is looming, with some suggesting it may be worse than the 2000’s crunch.
 
Recently we have seen the cost of food rising with all the primary cereals and meats having topped record highs in the past few years.  For you and I this is an inconvenience and possibly even a bit uncomfortable, but for the people at the bottom of the economic spectrum this is a crisis of massive proportions as they can no longer afford to feed their families properly.  The World Bank released a video clip (loaded onto our FaceBook page) which claims that 170 people fall into poverty every minute!!!  This is a staggering statistic and a very serious wakeup call that we cannot continue with business as usual.
 
I do not believe in responding to any of these claims in fear, however, ostrich tactics are no longer going to suffice.  However, I do feel that you and I that have a privileged position, as defined by having 3 full meals each day, a roof over our heads and education to at least Grade 12, have a moral obligation to get involved in finding solutions to assist those less fortunate than ourselves.  You may choose to see this as a business opportunity or a social responsibility, either way I encourage and challenge you to do what you personally can to alleviate the crisis ahead and the impact it is having, and will continue to have, on the least fortunate members of our society.  Aquaculture or Aquaponics may well be part of this plan but whatever you can do, do it.
 
 Wake up there is a crisis looming

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 December 05, 2016
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Wild caught vs farmed fish

BY Leslie Ter Morshuizen

Wild fish has largely been seen as `the best one can get' as they are expected to offer optimal nutritional quality and flavour, no risk of chemical contamination and certainly to be GMO free.  The reality is that taste trials comparing wild to farmed fish consistently reveal that panels are not able to distinguish between the two options.  Furthermore, nutritionists have shown that modern aquafeeds result in fish flesh that is as nutritious as the best natural products.
 
Consumer health is assumed to be assured when eating fish sourced from the wild, and I expect that this was true through history.  However, more recently, pollution of various sorts has compromised the healthiness of fish sourced from certain wild locations.  As many species are migratory, the level of certainty regarding their healthiness can be seriously compromised.  Farmed fish are maintained under managed conditions and can be reared without exposure to pollutants.  Although there is concern regarding the use of antibiotics and other therapeutics on farmed fish, the modern fish farm utilises very little, if any, chemicals or antibiotics, and if used, the standard approach is to select options that have a short half-life and are low risk.
 
Another form of pollution that is relevant, but this time aimed at the aquaculture industry, is genetic pollution.  Farmed fish are subjected to genetic improvement programs to select for desirable production characteristics such as rapid growth, disease resistance and high yield.  On the farm these traits are desirable, but when these fish escape they could breed with wild fish and alter the genetics of the natural stocks.  As it is impossible to improve on nature, any such change must be regarded as undesirable.  Fish farmers implement various strategies to reduce the escape of wild fish but certain infrastructure types, most especially cages, are not possible to secure with certainty.
 
The biggest factor in the debate is simply availability.  Yes, in the early days there were problems with aquaculture, as there probably were with any form of stock farming.  The Industry is cleaning up its act to minimise risk and impact on nature, and has advanced feed technology to ensure that the nutritional value of farmed fish is as high as it is in wild fish.  However, the relentless extraction of fish from every possible habitat in the wild has resulted in many stocks collapsing and others being close to the point of over exploitation.  We have reached or exceeded the maximum sustainable catch levels for virtually every stock and simply cannot harvest more from the wild.  By contrast, farmed fish production can easily be increased to meet growing demand.  In 2013 the mass of fish produced by aquaculture exceeded the wild catch for that year for the first time in history and the annual growth rate of aquaculture production is around 8% p.a.  As people realise that aquaculture actually is the greatest key we have to protect the remaining wild fish stocks, and as the virtues of farmed fish are becoming more widely known and accepted, greater support for the Industry is being obtained.  If we wish to continue eating fish we need to embrace aquaculture, and do so fast!
 
I recommend the following Ted Talk for those who wish to investigate this further.

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 December 05, 2016
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Why is aquaculture struggling?

BY Leslie Ter Morshuizen

Having been part of the aquaculture industry in Africa, and especially South Africa, for the past 20 years, I have formulated opinions on why the local industry does not appear to be growing as quickly as it should.  These opinions are not meant to offend, but are intended to clearly raise and illustrate hurdles which I believe need to be removed or significantly lowered for the industry to flourish.
 
There is far too much red tape for any new entrant wishing to invest in aquaculture.  If government is serious about growing aquaculture the number of permits and conditions associated with those permits need urgent attention to appropriately reduce the load.  This includes the complex and often largely opaque cross-Departmental rules which often strangle and trip up investors before they get to break ground or thereafter when they realise they have not applied for something they needed before commencing.  These cause time delays, wasted costs and result in frustration.  Sadly, many aspirant fish farmers have started and not completed process.  I call to the State to get the permitting in order so as to stimulate rather than frustrate the industry.
 
BBBEE is as evil as its predecessor Apartheid, except that with hindsight one would have hoped and expected that we would have learned that you cannot build by dividing.  I do not accept that it is meant to level the playing grounds and benefit those who were excluded by Apartheid; read the new BBBEE codes, they are specifically designed to create a small pool of `black industrialists’ rather than to grow the economy or uplift general population.  The true effect of BBBEE is to cause many of those who have skills and cash to take them and invest in other countries where the laws are not racially motivated.  This further dilutes the local talent and the economy.  Let’s learn from the past and scrap all forms of racially inspired legislation so that we can start working together to grow the economy and create jobs for the unemployed masses in our country.
 
Political instability.  I watched the Rand lose 40c to the US$ yesterday morning in a mere 2 hours following the National Prosecuting Authority laying charges against the Minister of Finance.  No one is above the law and if guilty every South African must have their day in court.  However, it is strange that the same NPA that has been unable/unwilling to charge our President on any of the more than 700 alleged charges, is able to quickly whip up a seemingly hollow case against the Minister of Finance!   The instability caused by the many dubious and often blatantly corrupt actions by a pro-Zuma State, leaves investors insecure locally and choosing to rather spend their ZAR elsewhere, where the political game and currency fluctuation are not as risky. If we wish to grow aquaculture in SA we need to clean up our playing field.
 
It is difficult to secure investment funding in aquaculture in SA.  White investors are again largely excluded by BBBEE or so compromised as to make a local investment unattractive, and non-white players often lack the skills, both on the aquaculture and business sides.  State `development banks’ are risk averse and where support is secured, payment is painfully slow, frustrating the business roll out and increasing the cost of the investment.
 
There is a national lack of technical aquaculture expertise at all levels from basic workers to senior managers.  Several Universities offer graduate and post graduate qualifications in aquaculture and there is a single Aquaculture Academy which offers practical training.  However, these alone are inadequate to grow the industry in line with the bold intensions of Operation Phakisa.  AgriSETA is in the process of developing new aquaculture training material, but the details of who will pay for this mass scale training have yet to be clarified.
 
South Africa’s climate is largely temperate with hot summers and cold winters, yet fish need to be grown all at an optimal temperature which varies according to the species.  It is therefore generally necessary to farm fish in an insulated, or semi-insulated, environment such as a warehouse or greenhouse to provide the ideal conditions throughout the year.  This adds to the capital cost and slightly increases the operational cost of rearing these species here versus elsewhere.  But the advantage is that we can offer year round supply of products to the market, a major advantage that harvest fisheries cannot offer.
 
Market access is a challenge.  The demand for fish is massive as has been confirmed by many independent surveys and detailed marketing investigations, but to penetrate the market and successfully maintain a market share requires significant capital and skill.  Funders typically require off-take agreements from the market before they will invest in a fish farm, yet the markets will not sign off-take agreements until they can inspect the processing factory and see the end product.  A catch 22!  Post-harvest value addition is a field that is largely undeveloped in SA, especially of the freshwater side beyond trout.  Opportunities abound but someone needs to foot the bill to develop the processes and products.
 
The economy of scale must be big for a fish farm to be truly profitable, yet the vast majority of people interested in entering the industry wish to start and operate a modest business.  Opportunities exist to club together and form a Satellite Grower Scheme, either for the entire process or merely in order to market products collaboratively.
When the above set of circumstances is considered in the light of Operation Phakisa and the stated desire by government to grow the aquaculture industry, I wish to propose that the State itself holds most of the keys needed to unlock commercial scale aquaculture in the nation.  In order for this to happen I strongly advocate that the State does several things, which will result in the private sector being able to run with the baton it is already holding in anticipation; these include:


  • scrap BBBEE and all other racial inspired laws and motivations; let’s together grow this industry based on economic principles to produce food and develop employment opportunities
  • streamline the permitting process to make the assessment of an application a simple, rapid process based on clearly defined appropriate environmental criteria sort out the politics!
  • if the president is a rotten egg get rid of him and his cadre, and replace them with honest leaders who are willing to stand against corruption, stabilise the platform and encourage international investment in SA
  • let the State fund the development of the market and especially of value added products based on catfish, tilapia and other species which hold enormous potential but have received little attention thus far
  • fund training centres that provide practical aquaculture training based on techniques and technology that is appropriate to the local environment
  • provide investment funding to all South Africans who wish to invest in the industry and have shown themselves to be skilled in both aquaculture and business 

Aquaculture has immense potential to create sustainable jobs in the rural areas, to develop a healthy protein and add significantly to the national economy, but will you as the State allow this to happen?

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 December 05, 2016
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A is for aquaculture

BY Leslie Ter Morshuizen

The world population is growing at an unprecedented rate and a major stable food source in the form of fish has been overharvested to the point that the supply from wild stocks is now diminishing.  Aquaculture, the farming of fish and other aquatic organisms, is the only reliable way in which we can meet the growing demand for fish.
 
Commercial aquaculture has been around for several decades, but only since the 1960s has production really increased rapidly.  Prior to this the oceans, rivers and lakes across the globe could provide sufficient food to feed people.  As the world population grew so did the pace at which we harvested fish from the wild, until in the 1990s we saw the capture fishery figures stagnating.  This occurred due to fishing pressure exceeding natural replacement rate, causing many stocks to crash to below the point of economic extinction.  Whilst the problem is easy to solve, simply stop fishing until stocks have recovered, this is not going to happen in a world where so many are dependent on fish for part or the bulk of their protein requirement.
 
Aquaculture has grown in response to the rising demand for seafood products coupled with the stagnating supply from wild harvests.  The Industry expands at an annual compounded rate of around 8.3%, and current production levels are flirting with 100 million tons p.a.  In 2013 the production from aquaculture exceeded the output from capture fisheries. 

Aquaculture has other more subtle advantages as well, including that it employs people in the rural areas, whereby working against the global problem of urban migration.  The Industry, with the exception of pond farming, is also a non-consumptive water user and the enriched effluent water is well suited to being used for crop farming.  Aquaponics is the ultimate expression of this, where the fish waste fertilises the growth of plants within the same system, purifying the water for the fish and resulting in 0% waste.
 
There has never been a better time to start your fish farm; the demand for many species is high and growing, and there are good options for profit.  However, as with any business, make sure you do your homework carefully and invest appropriately to ensure you have the best chance of success.

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 January 18, 2016
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Waste not, Want not

BY Leslie Ter Morshuizen
Following on the 2nd World War a generation of frugal minded people coined the phrase `waste not, want not’.  Having survived the horrors of war: food shortages, irregular supply of basic commodities, etc they knew what it was like to go without, and therefore saved and reused wherever possible.  The 2nd half of the 20th Century saw easier life in the West, and the mantra lost its’ significance.  However, as we progress into the 21st Century the saying is again becoming relevant due to the excessive demand on limited resources by an over populated world. 
 
Accurate feed management has always been important, but recently it has become critical to ensure that feed is being applied correctly, and that the economically best feed is used to minimise wastage into the RAS or environment.  However, no diet is completely digested, and we normally expect around 20% of the feed to end up as faeces.  In a RAS this matter is collected within the mechanical filter ASAP to avoid the reduction of water quality and then dumped out of the system.  Few in the 21st century would propose that dumping this into the river is acceptable but it is still generally viewed as a problem that needs to be solved.  There is another way to look at this organic material: it is a valuable nutrient source.
 
The mortalities that are removed from fish tanks each day are a loss to the farmer.  However, this is not a complete loss as the corpse is again a source of organic nutrients which also have value.  Viewed in this manner mortalities are no longer a complete loss, just a reduction in value.
 
Another critical area for saving is in the use of electricity.  Not only do we wish to reduce our electrical usage to cut the monthly bill but also to decrease the size of the backup generator we require to keep the systems running during power failures.  In this regard all processes on the fish farm need to utilise energy efficient designs and motors.  Our latest fish farm design incorporates a very low head in combination with extremely efficient pumps.  Visit our website for further information on these pumps.
 
The modern fish farmer therefore needs to develop a plan to utilise the nutrients in the effluent water stream and the mortalities, to turn these into a profit centre rather than merely a problem requiring a solution.  Various options exist, including aquaponics, silage, composting, biogas production and fertigation.  All of these processes solve the problem and create an income stream for the Business.  Furthermore, she also needs to be reducing reliance on electrical power through appropriate designs and efficient equipment.
 
Remember, waste not want not.
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 March 27, 2015
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Correct Feed Particle Size

BY Leslie Ter Morshuizen

Commercial fish farming depends on providing the fish with sufficient feed of the correctly nutritional quality to promote maximum, healthy growth. Although live feeds are important and serve numerous specific needs, it is seldom workable to feed fish exclusively on live feeds. We therefore generally rely on artificial feeds for the feeding of our fish to enjoy the benefits of bulk availability, storage and operational simplicity offered by this option. As artificial feeds are supplied in different pellet sizes, starting from a powder via crumble to a large pellet, we naturally need to know how to select the feed size that is best suited the cohort of fish being fed.

 

Obviously the gape of the fish’s mouth is the first factor to consider; if the pellet cannot fit into the mouth it will not be ingested immediately. As the pellet soaks water and softens, the fish will nibble at it, causing the pellet to fall apart and enabling the fish to eat pieces of the pellet. This causes large amounts of feed to be wasted as bits fall to the tank floor and certain elements dissolve into the water. However, it is equally important that the pellet should not be too small as the fish will usually not feed to satiation on pellets that are too small, especially in predatory fish where the size of the pellet is important to elicit an attack response.

 

If the pellet can fit into the gape of the fish, but only just, the fish tend not to digest the feed completely. This is evidenced by undigested pellets seen whilst inspecting the faeces. If the feed is not being digested it is clearly not contributing to growth!

 

Small fish require more protein in their diet than do larger fish of the same species, so the feed manufacturers include more protein in the diet of the smaller fish, thus in the smaller feed particle sizes. Feeding large fish on small pellets will therefore also result in unnecessary protein in the diet, which translates directly to financial waste as protein is expensive.

 

All this imprecision begs the question: `how do you know what the correct pellet size is for a group of fish?’

 

I do not believe that there is a simple one-size-fits-all type of solution due to the divergent dietary strategies employed by different species of fish. Predators tend to subdue and swallow large, infrequent meals whereas detritivores and herbivores are more inclined to nibble continuously. It is therefore necessary to consider the behaviour of the species you are farming in determining the most appropriate pellet size. However, the principle is that the feed particle must comfortably fit into the mouth of the fish. Practically, the pellet should be between ¼ to ½ of the area of the gape, with predators tending to receive larger pellets than other species. Ensure that the fish can comfortably eat the feed being fed, but err on the side of larger pellets rather than smaller pellets as this shortens feeding time and the fish tend to reach satiation more easily.

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 March 27, 2015
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Resolution: Live Sustainably

BY Leslie Ter Morshuizen
There are too many people on the planet, too few trees, too much pollution, too few fish in the oceans and many more “too’s” that illustrate the extent to which we have stretched the capacity of our planet to the limit.  Each of us is responsible for our own actions and this empowers us to make a difference based on those choices.  Either we can contribute to the demise of our planet or we can reduce our footprint, potentially even to a positive influence.
 
This is the time of year when we all take stock, decide where we feel we need to improve ourselves, set resolutions and make goals that we believe will take us in the desired direction.  I put the challenge to you to consider resolutions that can enable you to live more sustainably in 2015.  Whatever you currently do to reduce your environmental impact is excellent, but there is always more that can be done!
 
Examples of such measures include composting your kitchen waste, producing earthworms on the kitchen scraps, catching and drinking rainwater, walking wherever possible instead of driving, turning your geyser temperature down, capturing the sun’s energy to heat your household water and insulating your home to reduce heating requirements.  These all move us in the right directions, but what about growing your own vegetables, and how about using aquaponics as the technique?
 
Low energy pumps are adequate to circulate the water in an aquaponics system, keeping energy usage to a minimum.  Placing the tanks and growbeds inside a greenhouse tunnel enables us to reduce winter & night time heat loss, whilst capturing daytime solar heat, thereby providing a superb growing environment for our plants.  The crops themselves can be grown from heirloom seeds (non-modified seeds, aka natural seeds).  No fertilisers are required as the fish waste provides the nutrients the plants need, with the exception of a supplement of alkalinity and occasional additional of chelated iron.  All this to produce the tastiest plant crops (and fish!) you are likely to encounter anywhere.
 
If we each do what we can to make our living space as environmentally friendly as possible we can reduce the impact we are having on the planet, whilst also enjoying the literal fruits of our labour.
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 January 27, 2015
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Economic Viability of Aquaponics

BY Leslie Ter Morshuizen

Economic Viability of Aquaponics

 

When we started our 300m2 Aquaponics Facility in late 2012 we did so with the following specific goals in mind:

  • Test and refine which crops did the best under Aquaponics
  • Quantify the technical variables to optimise the design
  • Establish appropriate planting densities, cropping times, etc
  • Confirm the economic viability of Aquaponics in SA

Over the two years of running this system we have learned a great deal about the crops and market, we have made a few technical changes to the system and we have confirmed the best crops for our situation based on our climate, market and system design. In addition, we have learned what it takes to run a financially viable aquaponics facility.

 

The question of financial viability is one that is often asked concerning aquaponics - `is it a viable business?’ From what we have seen Aquaponics can be profitable but in order for this to occur you need to have several `ducks in a row’, and in no particular order of importance these `ducks’ would be:

 

Crop Selection

Forget about the fish they are almost irrelevant, in Aquaponics it is the vegetable crops that earn the revenue. Selecting the correct plant crop is therefore of paramount importance to economic viability in Aquaponics. Initially we produced mountains of the most incredible quality basil, but fed it to the earthworms as we could not sell 120kg basil p.m. in Grahamstown. We investigated sending it to Port Elizabeth and even secured an off-take agreement for the full amount, but in order to profitably serve this market we would have to erect several more tunnels.

We learned from this initial error and spoke to local restaurateurs to establish which crops they would be interested in purchasing. Following their advice we switched to producing a range of vegetables and herbs, and most grow incredibly well. On marketing the crops we learned the next valuable lesson – because the plants grow well and the market wants it does not mean that it is profitable to grow! Swiss chard, butternut and beans are good examples of crops that grow extremely well (and the swiss chard grown in aquaponics is not gritty!) and are in high demand, but the prices do not justify the effort involved. Over time we refined the crops to those that enjoy a healthy market demand but are optimally profitable to produce. Our production is now based on cucumbers using the vertical space with herbs covering the horizontal area.

 

Keep the Pests under Control

I would love to find an organic product that is also truly effective at treating sap sucking pests! The range we use works fairly well but every now and then we are over whelmed but aphids and have to take control to avoid reduced production or even losing the crops entirely. Watch carefully for those pests and treat early and often.

 

Every Piece of Growbed must be Planted

Aquaponics in a temperate climate generally occurs inside a greenhouse tunnel. Active heating keeps the water near optimal temperature levels for the plants and fish, resulting in good growth of both. Such infrastructure is expensive to install and must therefore be operated so as to maximise output. The growbeds must remain fully planted at all times, aging plants must be removed to make space for young, more vigorous plants and the fish tanks must enjoy proper stocking densities.

 

A High Market Price is Vital

Again, because of the high capital cost of Aquaponics, it is necessary to secure a high price for the crops and fish being produced. This is as important as producing the maximum quantity of crops from the infrastructure.

 

In conclusion, when run properly Aquaponics certainly can be profitable, so much so that we made our first profit distribution to stakeholders last month. Viva Aquaponics!

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 October 28, 2014
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Feeding to Satiation

BY Leslie Ter Morshuizen

How Much to Feed My Fish?

 

A recent article on SARNISSA created a small storm in my inbox! For years I have been training fish farmers to feed to satiation, yet here a respected colleague mentions the method in brief and dismisses it as being `not recommended’. I wish to defend my position, not because it is mine but because I firmly believe that it is the most economically viable method of feeding your fish and it is also the easiest to get right.

 

Why did my colleague dismiss satiation feeding? I believe that this is because his experience is largely based on feeding trout with sinking pellets. Given this assumption, I 100% agree that feeding to satiation is very difficult to implement accurately; under- and over-feeding are direct risks with economic and water quality consequences. However, I firmly believe that sinking pellets are old school, a competent feed manufacturer can produce a high quality floating pellet (certainly in the sizes above 1mm diameter) which is perfect for satiation feeding.

 

Satiation feeding is highly recommended as it is both flexible and simple. Water temperatures, DO levels, time of day, etc all affect the amount of feed a group of fish will eat at any particular meal. With satiation feeding we provide small batches of feed sequentially and continuously until the fish have had sufficient to eat. We know that they have had enough to eat when their rate of feeding slows down, i.e. before it stops completely. Water quality parameters and other variables that affect the hunger of the fish at each meal time are taken into account by the fish themselves, thus removing the massive complexity associated with predicting feed requirement per meal using fish mass, fish quantity and feeding tables.

 

Using floating pellets, even a novice fish farmer can easily monitor the feeding response to continue feeding whilst the fish are hungry and stop when feeding slows. In this way both under- and over-feeding are both simultaneously avoided, allowing for maximum growth and minimal size differentiation per cohort. Using this method we have obtained FCRs of around 1:1 even with tilapia, a fish that normally offers a FCR around 1:1.5, with very real economic benefits!

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 October 28, 2014
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Stationary Submerged Mechanical Filters

BY Leslie Ter Morshuizen

Our society seems to believe that the more technology we throw at an obstacle the better the solution will be. In the previous eNewsletter on drum filters I mentioned that they were efficient and capable of removing small particles, but that they are very expensive and waste lots of water during cleaning, and as such do not represent the silver bullet we are looking for in solids removal.

 

Another method of solids removal is the stationery, submerged mechanical filter (SSMF). This is a broad category of filters that use a coarse media to allow for free water flow. As the water passes over the filter media, the solids settle against the media due to friction between the media and water causing localised low water velocity, which results in settling. The photographs below show examples bioblock (left), corrugated plastic blocks (centre) and bird netting (right), all of which are well suited to this application although the efficiency of the netting is difficult to predict due to its’ irregular volume and inconsistent shape within the water.

 

Coarse stone (19mm) was also used in the early days of recirculating aquaculture, but is extremely heavy and therefore requires enormous effort to clean. This makes it a less desirable option other than in Aquaponics where the size of the bed is enormous compared to the amount of fish waste it needs to deal with and blocking is less of a problem.

 

The ability of SSMFs to clean water is a function of various parameters, primarily the coarseness of the media as compared to the flow velocity through the media. Fine media with a slow flow rate is most efficient but blocks the quickest, whereas very coarse media with a faster flow will take longer before cleaning is required, but will occupy a massive volume within the system.

 

SSMF are generally installed in multiple parallel chambers so that one can be cleaned without interrupting the flow of the RAS. To clean a chamber we then isolate the chamber from the rest of the RAS, lower the water level slightly and rinse the media in that chamber. The dirty water is then dumped, the chamber rinsed, the media replaced and water again allowed to flow through the chamber.

 

At first glance it may seem that this cleaning wastes a lot of water, but the reality is that SSMFs actually waste less water than drum filters to perform the same function. SSMFs also need less frequent cleaning than bead filters and are not especially expensive filters to install or operate, making them a great choice for many aquaculture situations.

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 July 09, 2014
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Fish Health Management

BY Leslie Ter Morshuizen

Fish health video clip

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 May 29, 2014
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What is Aquaponics?

BY Leslie Ter Morshuizen

Video clip providing a brief explaination of what Ebb & Flow Aquaponics is about

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 May 29, 2014
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Breeding African Catfish

BY Leslie Ter Morshuizen

Video clip on the breeding protocol for African Catfish

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 May 29, 2014
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Why Catfish is the Fish of the Future.

BY Leslie Ter Morshuizen

One regularly hears the statistics on the pending population explosion, environmental collapse and food shortages. At the risk of labouring the point I wish to raise a few issues that I believe are pivotal to our society in terms of the way we function at present and the inevitable change that I believe lies just ahead of us in terms of:

  1. Population growth – the global population is currently believed to be around 7.2bn people and growing by a further billion individuals every 12 years (www.worldometers.info)! The scary part of this is that it is estimated that the maximum sustainable global population level is around 2 billion people, meaning that there are already 3.5 times more people than the planet can support at a European standard of living (www.worldpopulationbalance.org) and the population is still expanding rapidly.
  2. Food shortages – if we consider fish supply as an example, the annual harvest of wild fish has only been maintained at more or less constant levels by using increasingly sophisticated technologies and harvesting stocks that were previously unfished. The prediction (made in the 1970’s) that fish stocks would peak in around 2000 and be stable for 15 to 20 years is the state we are currently in. They concluded with the prediction that there would be a spectacular crash in stocks 15 to 20 years later, and we are now entering this time frame. The writing is on the wall.

Another view on this is the development of genetically modified seeds for agriculture (The Future of Food). The companies’ spin doctors tell us it enhances disease resistance, increases harvest per plant and is resistant to herbicides (also sold by the same company) whereas the sceptics tell us they are downright bad for us and should not be eaten as they contribute to, or cause, a range of health problems. A colossal threat with this though is that the companies are able to patent their seed and if any trace of their genetic material is found in your crop (even through wild pollination!) you get sued for using their product without licence. How then do the thousands of subsistence farmers throughout Africa feel about seeds from the large corporates, Monsanto and their kin, being spread throughout Africa? I see trouble coming.

 

It is clear to me that our global society cannot continue tomorrow in the same manner that we are living and doing business today. Wild stocks have been harvested beyond the point from which many species can recover even if we stopped fishing for them. Massive global seed companies are commercialising agriculture to the point that they threaten the livelihood of the subsistence farmer and the commercial farmer who chooses not to use their products. Other resources such as natural forests are being denuded at an alarming rate to make way for crop farming, grazing or housing developments. But these forests are the lungs of the planet and without them we are already seeing significant changes in weather patterns, storm frequency and intensity, drought and flooding that many experts attribute back to the reduction of these forests.

This is not news, and on the positive side there is already is a strong move towards healthier diets, cleaner energy and reduced footprint on the planet, but I fear it is too little and too late. Too many of us have been sceptical or indifferent for too long, and we have passed the tipping point beyond which recovery is simple. The documentary film `The End of the line’ contains two priceless comments which sum up the situation: `compared to other problems this (rebuilding wild fish stocks) is relatively easy to fix’ and ` but man is not going to change and the sea is going to be dead’!

 

Given the rampant growth of the world population and the increasing shortfall in supply of foods, food cost will continue going up. This once again is not news and we each see in our daily lives how much it costs to feed our families. As feed prices increase people do look at alternative options that offer healthy food at an affordable rate, and farmed fish certainly is such an option. Tilapia was barely eaten in the formal sector in SA 10 years ago, now there is a growing demand for it as people have found marine fish to be unavailable, tried tilapia and found it to be a superb tasting fish. I do not believe that it will end there, as the economic conditions tighten, people will continue looking elsewhere, and `I put it to you’ that the ultimate answer is catfish (Clarias gariepinus).

 

The sharptooth catfish is probably the world’s ultimate aquaculture species from a technical and an economic perspective. They can be farmed at super high densities without the need for aeration as they are air breathing, and with a slow water exchange rate due to their high tolerance of metabolic wastes in their water. Furthermore they offer a better FCR than tilapia (we currently achieve <1:1 on our catfish) and they do well on a floating pellet, simplifying management. Growth is exceedingly rapid and they reliably attain 1kg in 6 months. Infrastructure cost is therefore relatively low due to the high stocking density, simply water reparation technology and fast growth rate this fish offers.

 

The net result is that catfish is the cheapest fish to farm. Their air breathing ability means they can be transported alive with minimal water, keeping them absolutely fresh until slaughter. Add to this the ability to obtain two long, boneless fillets off the fish and we have a winner. This fillet is very versatile and can be turned into a wide range of culinary delights, opening up the formal sector markets.  Finally, the flavour of catfish is fishy but only mildly so. As a lady on a marketing trial recently commented: `if I eat catfish I can go out visiting afterwards which I cannot do if I had eaten pilchards’.

 

Given that the demand for food is as big as it is, and given that catfish is such a fantastic and inexpensive fish, why then do we not see it more widely eaten? In Nigeria, Cameroon, Uganda and more recently Hungary, catfish has already been recognised as a 1st class fish and in other parts it is slowly becoming more widely eaten. Some people will not eat catfish due to its lack of scales offending their religious code, whilst others simply do not like the appearance of the barbels or believe that they are eating a scavenger.

Whilst these may all be true to some degree, I predict that as the demand and price for food increases people will switch to eating catfish, and once they have changed they will see this is a great eating fish and it is a lot cheaper than the alternatives. I believe that catfish is the fish of the future!

 

 

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 May 05, 2014
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Bead Filters

BY Leslie Ter Morshuizen

No discussion of mechanical filters in aquaculture would be complete without the mention of bead filters because, although they are fairly expensive, they are effective at cleaning aquaculture water.

 

A bead filter is basically a pressure sand filter housing that is plumbed with a screen at the top as well as the normal screen in the bottom of the unit. 3mm plastic beads are added to 40% of the volume. As the beads are positively buoyant they float, forming a layer in the top ½ of the filter. The beads must be made of non-toxic plastic, so virgin material is often used.

 

Water enters the bottom of the bead filter and travels up through the bed of beads. Particles being transported by the water get stuck in the bead bed and the clean water exits the top of the bead filter.

 

To clean the filter we stop the flow through the unit and open a drain valve so that the water inside the filter can drain away to waste. (Use this water on your garden it is fantastic fertiliser!) While the water is draining out you should open the port on the top of the filter and use your hand to give the beads a good stir to dislodge trapped particles and break up any clumps of beads that may be forming. A few buckets of water are thrown in once the water has drain out to remove the last dirt and then the filter is closed up and normal flow resumes, except that the first water coming out the top of the bead filter should again be dumped as it also contains fine particles which we want to get rid of.

 

Bead filters are excellent in low solids load applications, such as koi ponds of ornamental fish RAS. However, the fairly small bead volume tends to block too quickly in food fish farming, requiring frequent backflushing. However, multiple bead filters can be used in parallel with great success even with food fish farming.

 

Another major benefit of bead filters is that they are simultaneously effective at both mechanical and biological filtration, reducing the need for additional filters. Scientific studies have shown that the wastes from up to 32kg of feed can be trapped and the resultant ammonia converted to nitrate per m3 of beads per day!

 

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 January 06, 2014
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Economy of Scale

BY Leslie Ter Morshuizen

When asked for a definition of aquaculture we typically say something along the lines of `the farming of aquatic organisms’. Whilst this is true it is only a part of the story. In reality aquaculture is a BUSINESS, if we forget this part of the definition we are doomed to failure.

 

The bi-annual Symposium of the Aquaculture Association of South Africa was held in Stellenbosch last week and attended by delegates from a large number of countries. Several of the speakers made points that paralleled each other, and production scale was one such topic. These presenters stressed the importance of being large enough to be profitable despite the high cost of fish feed, distances over which produce needs to be delivered, staff & wage issues, disasters and other routine or unexpected events that drain money off the bottom line. Furthermore, large scale producers are able to gear the economy of scale to increase their profit line, make use of technical services, can increase efficiencies and are able to negotiate better marketing terms than small producers.

 

Where then is the place for the smaller producer? I believe that there are two possible routes one can follow when starting an aquaculture venture: either, start small, learn from your mistakes and then build on your successes to grow, or alternatively start large enough to bring in qualified, experienced managers. If the 1st instance, you are on a small scale and will tend to have to dance to the tune of the suppliers and marketers, but once you increase your production to a large scale you will be better positioned to negotiate, both with suppliers as well as markets. However, there are instances where unique advantages enable the small operator to profitably supply local niche markets where the larger producers cannot compete in as cost effectively. Typically service would be a differentiating factor in the favour of the small producer.

 

There is also characteristically an economic black hole between small and large scale production levels and profit is very difficult to achieve in this void. Consequently, to move from being a small scale to a large scale producer usually requires a substantial injection of faith and cash. Make sure you have done your homework so that the balance between optimism and realism is correct, and remember that whilst aquaculture involves farming aquatic animals it must first and foremost remain a commercial undertaking.

 

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 December 02, 2013
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First Identify the Cause

BY Leslie Ter Morshuizen

Fish health is not complex; keep stress to a minimum and the fish have the ability to fight off most disease attacks and remain healthy. The key word is stress and this can be present in many different forms, almost all of which are within the control of management. Prior to introducing fish into an environment we also need to ensure that they are free of parasites, reducing the risk that parasitic load itself can become a stress factor.

 

The water parameters must be excellent and appropriate for the species you are farming, the feed must be high quality and provided in sufficient quantity, and all handling needs to be done gently. Social interaction needs to be appropriate and the theory that lower is better is not always true. Many fish species are communal and feel stressed at low densities. Every species I can think of performs better when surrounded by other fish than it does on its own, even if the companions are of a different species.

 

When we notice that our fish are unhappy it is therefore imperative to investigate the range of causes and isolate which factor is creating the stress in order to decide upon the most appropriate method of reducing the stress and allowing the fish to recover. All too often fish farmers are tempted to treat the conditions with what they perceive to be the best approach, or perhaps a silver bullet, without first investigating the true cause factor. Most treatments involve water temperatures or chemical additions that are themselves stressful to the fish, and should not be administered without careful consideration. If you use an inappropriate treatment this adds stress to a fish that is already dealing with sub-lethal stress levels, and the additional trauma can be the final straw that kills it.

 
The solution is fortunately simple, keep the fish under optimal conditions and they will almost always be happy and healthy. If you do suspect a problem investigate first to identify the cause of the problem and only then decide on an appropriate path of action to follow.

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 November 04, 2013
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Who is the Jockey?

BY Leslie Ter Morshuizen

Potential investors often ask me what I need to know when advising them in order to assess whether their proposed aquaculture venture will be profitable or not, and seem surprised when I ask `who is the jockey?’ After several years in the industry I am more convinced than ever that management is by far the biggest factor separating successful operations from those that are mediocre and those that fail outright.

 

There certainly are different management styles. I remember a farm on the Zululand coast that was run by an entrepreneur who appeared not to believe in maintenance as this ate into his expansion budget, whereas others choose to do things in stainless steel and glass. Both can be successful as this is not the determining factor. Some farms run on a skeleton of staff whereas others seem to have an abundance of manpower; this too is insufficient to differentiate success from failure.

 
What I have observed is that those managers who are detail orientated and production focussed appear to be the ones who most commonly succeed. Naturally to this we need to add a long list of skills including a hawk-like focus on cashflow, ability to work with people, higher than normal energy levels and an appetite for risk and reward. On site the manage also need to be sure that operation expenses are being managed, especially feed usage efficiency and that the best possible price is obtained for every fish sold.

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 August 05, 2013
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