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Integrated Aquaculture

Imagine being able to produce your own freshwater fish and salad – simultaneously – in your own backyard.

Well, you can…..using integrated aquaculture.

The three important elements in any integrated aquaculture system are plants, fish and beneficial microbiology. Put simply, you feed the fish, the microbes turn the fish wastes into plant food and the plants clean the water for the fish.

The best known manifestation of integrated aquaculture is aquaponics – the combination of intensive aquaculture and hydroponics.  Aquaponics is not, however, the only way to integrate the production of fish and plants.

While the fish and plants are the visible elements of the integration, it’s microbiology that makes it all possible.  While this microbiology is very complex, the aquatic nitrogen cycle is easy to understand and is the part that allows for  the conversion of toxic fish wastes into plant food.

Nitrogen Cycle

The waste produced by the fish breaks down to produce ammonia.

When the ammonia levels in the fish tank reach a certain level, bacteria (Nitrosomonas) begin to colonise the system. As the numbers of these bacteria build, the ammonia (NH3) is converted to nitrite (NO2). As the ammonia levels drop, the nitrite levels increase. The nitrites (like ammonia) are toxic to fish.

When the nitrite levels in the water reach a certain point, other bacteria (Nitrobacter/Nitrospira) begin to colonise the system. These bacteria convert nitrites to nitrates (NO3), which are far less harmful to the fish.

While the microbiology associated with aquaculture is complex, the equipment needed is very straightforward.

To produce freshwater fish in your backyard, you’ll need:

  1. A fish tank
  2. A pump and some fittings
  3. Mechanical and biological filtration

That’s it! These three components comprise a basic recirculating aquaculture system. You just add water and some fish……and start doing some water tests.

The first successful closed loop integration of fish and plants was called the Integrated Aqua-Vegeculture System (iAVs).  It was invented by Dr Mark R McMurtry in 1985.

In its simplest iteration, iAVs consists of a fish tank and sand bio-filters. 

Subsequent developments saw the emergence of what became known as aquaponics…the integration of recirculating aquaculture and hydroponics.  

Aquaponics comes in many forms but the dominant systems are:

  • gravel culture – flood and drain aquaponics
  • deep water culture – raft aquaponics

Both recirculating aquaculture and hydroponics create a waste stream.  In a conventional recirculating aquaculture system, nitrates are removed through water replacement where a predetermined volume of water is dumped each day. In a conventional hydroponic system, inorganic salts are used to provide nutrients for plants. Once the nutrient levels drop below a certain level, they are also dumped. In both situations, the wasteful disposal of nutrient-rich effluent creates environmental issues.

When they are integrated, however, the waste streams are reconciled – to the benefit of both fish and plants.

Integrated aquaculture is not limited to iAVs and aquaponics. There are also a number of soil-based options.

Since they all grow plants, the choice of a particular system boils down to personal preferences and the availability of resources.

Regardless of the method used, integrated aquaculture differs from conventional horticulture in a number of important ways.

The first (and most obvious) distinction is the source of nutrients – the fish.  Integrated aquaculture effectively provides two crops – one is fish and the other plants – for the same volume of water that it would otherwise take just to grow the plants.

The other very important difference is that, since chemical herbicides or pesticides are toxic to fish, they cannot be used in recirculating systems.  Clean chemical-free food is the result.


The list of Australian freshwater fish that can be produced in a backyard includes:

  1. Barramundi
  2. Murray Cod
  3. Silver Perch
  4. Jade Perch
  5. Sleepy Cod
  6. Eel-tailed Catfish

Freshwater crayfish include Yabbies (Cherax Destructor), Redclaw and Marron.

Every region throughout the world has its own freshwater fish species.

Pelletised rations, specially formulated for native freshwater fish, are available from fodder stores.


Integrated aquaculture lends itself to virtually any plant…particularly food plants.  The specific method will vary according to the type of plants being grown.

I’ve been engaged in integrated aquaculture since 2005…and I’ve written hundreds of articles on the subject.  In fact, I self-published what was arguably the first book on the subject in the world (The Urban Aquaponics Manual) back in 2007.  This material is being reviewed and will be available on this site.

This article was first written in 2009.  It was reviewed in September 2017.

How iAVs became Sandgardening

In early 2020, as a global pandemic passed across the world, I embarked on a quest to understand more about the most commonly available substance on the surface of the planet…sand!

My sand story actually began in 2014 when I commenced what was to become a six-year apprenticeship…and an almost daily collaboration…with Dr Mark R McMurtry…the inventor of the Integrated Aqua-Vegeculture System (iAVs).

Simply put, iAVs is a gardening method that utilises the metabolic wastes of fish to grow fruit and vegetables…using sand as the growing medium.

McMurtry’s motivation was to find a means whereby impoverished villagers could derive their nutrition without harming the planet. iAVs was the result.

Following its investigation at North Carolina State University, iAVs was judged to be a big deal by some of America’s leading horticulturists and, for a time its fortunes seemed assured.

Long story short, fate conspired to see iAVs relegated to obscurity…and that was how I found it in 2014. when I committed to bringing about an iAVs renaissance.

In early 2020, I sought to reconcile our efforts to bring iAVs to a broader audience with what we’d achieved and it wasn’t stacking up.

We had made modest inroads – and many mistakes – in our efforts to draw attention to the method. A small band of backyarders had expanded to include farmers in countries like India and Egypt who had taken up the method…and their results confirmed the claims made for iAVs.

But, when I looked at the effort that was required to continue…and I considered what still had to be done…in the face of increasing years and declining energy levels…I realised that I either had to get a better return on the investment of my life energy or find something else to do.

I was tired of the struggle and I could easily have left it at that – but for three things…Dr Mark R McMurtry, the Integrated Aqua-Vegeculture system and a couple of questions.

I’ll talk more about Mark a bit later…but just so we’re clear, I regard the iAVs method as the jewel in the integrated aquaculture crown. It is a ‘living machine’ and a great example of waste transformation farming – indeed it’s the logical starting point for practical purposes. It is technically elegant and arguably one of the fastest ways to put clean fresh food on your table.

I think that it’s a contender for the most productive, resilient and sustainable food production system ever devised.

Suffice to say, I love iAVs.

But I did have some questions.

Question 1…”After six years of strident advocacy for the iAVs method I never actually built one. Why?”

It’s a good question and one that I have yet to satisfactorily answer for myself – much less anyone else. For a long time, I used the excuse that I had no suitable sand…and then I got suitable sand…and I had no time. Then I got time and I built two 8′ x 4′ sand biofilters and a sump tank. I recirculated water through the system and offered more excuses for my failure to add fish.

There was something that was making me decidedly uncomfortable about actually starting up my own iAVs but I couldn’t quite put my finger on it.

And then the penny dropped.

It was the fish.

After 16 years of building and operating small-scale recirculating aquaculture systems, I came face to face with the realisation that I really no longer wanted to keep fish. In a sense it was the quest for a better way of integrating fish and plant production that led me to iAVs…but I had learned most what I wanted to about rearing freshwater fish…and I finally admitted to myself that, when it came to eating them, I much preferred marine species anyway.

But, at the same time, I was still fascinated by iAVs.

I guess it was inevitable, therefore, that Question 2 would arise.

Question 2…”What if we just wanted to grow plants – in the sand – in a recirculating arrangement – just like iAVs – but without fish?

If the fish in an iAVs are the organic nutrient source for the plants, what if we built an iAVs with a different nutrient source?

I understood that iAVs without the fish wasn’t iAVs…but iAVs was always more about plants than fish anyway.

Was there a place for an organic plant production system – based on sand – that did what iAVs did – without the need to grow fish?

In the ensuing weeks and months, I set out to learn more about the history of sand use in horticulture.

I dragged out my old hydroponics books and read about the sand hydroponics installations that had existed – dating back to the 1940’s.

That confirmed for me that growing plants in sand had a history…a proud and diverse one…ranging from the Bengal system described by J. Sholto Douglas to the large WW2 US Army installations on Pacific atolls. Not only was I struck by the diversity of sand hydroponics systems but also their size.

In recent years, sand hydroponics had given way to lighter media like Rockwool and coco coir – and different methods like deep water culture and the nutrient film technique.

But the fact remained, that sand hydroponics worked very well until it was displaced by the convenience of other methods and media…that convenience made possible by cheap energy.

The cheap energy also provided most of the inorganic salts that are used to manufacture plant nutrients.

Even sand hydroponics suffered from the need to use inorganic salts.

I wanted an organic plant production system that used sand as media and evidenced the same capabilities of iAVs – but without the fish.

I recalled seeing allegedly organic bat guano preparations in hydroponics retail outlets…but the price and the source didn’t fit in with my emerging vision of a fish-free iAVs.

As I pondered the organic alternatives to the metabolic wastes of fish, I turned my mind to a name for a garden that used sand instead of soil…one that functioned like hydroponics but used organic nutrients in place of the inorganic salts.

And it had to demonstrate similar productivity, resilience and sustainability to iAVs…without the fish.

I wanted people to be able to embrace iAVs where practicable but to be able to access something different if, for whatever reason, they were unable to use fish.

The key feature of iAVs is sand…and its inventor affirms that (although fish provide the nutrients) he regards iAVs as a horticultural method…gardening…where the fish are the means to the end.

Question 3…So, if an iAVs can’t be an iAVs without the fish…what are we left with?

Sand + gardening = Sandgardening.

Sandgardening…the production of fresh organic food using sand as a growing media.

The idea that gave rise to sandgardening came from iAVs…and sandgardening is evidence of my belief that the iAVs method offers even greater scope in other organic iterations.

So, iAVs is a variant of sandgardening…indeed ‘the state of the art’…it’s our north star…the framework – and the benchmark.

Sandgardening is broader in its approach…and offers other variants for those who cannot – or will not – keep fish…but want to be able to grow their own clean fresh organic food.


Why Waste Transformation Farming is the Future

Industrial farming has wrought incalculable damage on our planet.  As such, it is unsustainable.  We need alternative ways to for us to derive our nutrition without devastating our place…Mother Earth!  

Waste Transformation Farming is that method.

It also means more income, better health and greater food security for those who embrace it.

WTF is productive, resilient and sustainable.

Productivity is the rate of output that is created for a unit of input. It’s used to measure how much you get out of an hour worked – or a dollar of investment. It follows, therefore, if you don’t have to pay (or pay less) for livestock feed and fertilisers, you are more productive. WTF offers unparalleled productivity.

Resilienceis the ability for a system, entity or individual to endure stress. It’s how well you take a hit…and how well you bounce back.  If you’re not in debt to feed and fertiliser suppliers, and you have a diverse range of products, you’re in a better position to cope with market downturns and adverse weather events…while still putting food on your table (literally).  WTF is the most risk-averse way to farm.

Sustainability, in a WTF context, means deriving your nutrition and livelihood without harming the planet.  No chemical pesticides or herbicides.  No chemical fertilisers.  No production systems that produce toxins.  No discharge of effluent to groundwater.  WTF is arguably the most planet-friendly act that you could undertake.

The availability of fresh water is one of the more pressing limits to world agriculture.  WTF embraces integrated aquaculture strategies that mean that you will use much less water (than conventional farming) …or it will provide you with unparalleled productivity for the water that you currently use.

WTF provides for biological and financial leverage.

Leverage is your ability to influence the outcome of your efforts – without a corresponding increase in the consumption of resources.  It occurs when we integrate two or more food production systems.   Integrated systems are always more than the sum of the parts. They’re the agricultural equivalent of 2+2=5 (or more).

When we gather the manure from chickens and feed it to black soldier fly larvae and worms we get not only eggs but also live animal protein for chickens and fish, excellent soil amendments…for no added cost.

WTF is infinitely scalable.

You can practise waste transformation farming in your backyard.  You can set up a social enterprise to empower impoverished villagers.  You can expand a backyard micro-farm to become a commercial enterprise.

To summarise…WTF will provide more food – of better quality – in a shorter time – at lower cost.  It will give you more for less!

And our planet will love you for it.


The next article will look at WTF from a practical perspective.  We’ll walk you through HaveMore Farm…our very own waste transformation farm.

If waste transformation farming interests you, and you’d like to talk about it with other like-minded people, feel free to take up membership of my Have More For Less forum.

Fish and Salad…Again?

Integrated aquaculture is the centrepiece of any waste transformation farm (WTF).

Not only is it an excellent example of the WTF principle of making use of the waste products of one organism as the feedstock of others, but it’s also the fastest way to put homegrown food on your table.  You can plant the seedlings of Asian and salad greens today and sit down to your first homegrown food about eighteen days later.  

The first time you eat fish and salad – grown by your own hand – is a great day.

But, even barramundi and a Greek salad, gets monotonous once you’ve had it a couple of dozen times.

People often refer to aquaponics as being an eco-system. For as much as that’s true, it’s a very skinny and unstable eco-system.  The ‘fish and salad’ approach to integrated aquaculture (iAVs or aquaponics) is not only dull from a culinary perspective – but it’s also limited in terms of its waste transformation potential.

Aquaponics generates wastes other than fish poop and metabolic ammonia. There are all of the plant residues that result from those vegetables we eat. Sometimes, we grow more fruit and vegetables than we can eat.

But it doesn’t end there.

Periodically, fate takes a wrong turn and you end up with a tank full of dead fish.   Even when the gods are with you, you’ll end up with a bucketful of heads, guts and scales after a couple of hours of cleaning your fish harvest.  I almost cry every time I hear somebody say that they buried their dead fish – or the processing residues from their fish.

The very least that should happen to a dead fish is that it should be made into fish hydrolosate – a potent organic fertiliser that can also be used as a high protein feed additive.

Fish mortalities – and the processing wastes from fish – are very high in protein. Fish (in any one of several forms) – and plants  – are 2/3 of a chicken’s diet. 

Once you integrate chickens into the food production system, your menu is looking so much more interesting for the eggs and meat that they will provide…and they cost you far less than normal because you’re getting most of their food from things that would be discarded or (at best) be thrown onto the compost heap.

And chickens are just the tip of the waste transformation iceberg – where even your plate scrapings have value.

If waste transformation farming interests you, and you’d like to talk about it with other like-minded people, feel free to take up membership of my Have More For Less forum.


Sayonara Aquaponics

In recent weeks, I’ve been reflecting on aquaponics – and its impact on my life.

I wrote the Urban Aquaponics Manual back in 2007 – and then revised it three times – and I’ve been endeavouring to roll out the 4th Edition for several years…but I struggle to make the time to complete the work.

I’ve designed and built a dozen systems…and I currently have my latest creation ready to go…but I lack the motivation to even find the fish and start it up.

I’ve spent about 13 years on various discussion forum and Facebook groups and that has brought me into contact with the full spectrum of humanity ranging from the delightful to the absolute arsehole…and I’m tired.

Part of my problem with aquaponics has to do with my introduction, in 2014, to iAVs…the method that best demonstrates what integrated aquaculture looks is really about.

Suffice to say, I’ve been at the aquaponics crossroads for some time…but the disenchantment has peaked in the past couple of weeks.

About a week ago, Permaculturist David the Good released a YouTube video called “The Aquaponics Delusion – Why Aquaponic Gardening Doesn’t Make Sense” in which he canvassed his concerns with aquaponics.  The ensuing reaction from elements of the aquaponics community caused David to pull the video but the gist of his argument can be found in this article.

While article had some shortcomings, enough of it resonated with me that it became the straw that finally broke the aquaponics camel’s back.

My problem with aquaponics is exacerbated by other personal issues.  Suffice to say, I have too many projects – and too little time – to the point where I’m not achieving anything except to frustrate myself and others.

As things stand, right now, I’ll be selling my latest (unused) recirculating aquaculture system.  I’ll also be calling a halt to the rollout of the 4th Edition of the Urban Aquaponics Manual…at least until I’ve cleared the backlog.

I’m not abandoning integrated aquaculture…simply changing direction.