What is Aquaponics?
If you’re looking for the next step up in food production, Aquaponics could be perfect.
Aquaponics is a “discipline” that has evolved from taking the best of aquaculture and the best of hydroponics. Where aquaculture only grows fish, and, hydroponics — plants, Aquaponics is a natural system that grows fish and plants, usually vegetables, together.
The system includes a tank for growing fish and grow beds for the plants. The grow beds and tanks can be any size, shape or material but the best material is fibreglass. The water from the fish tank, including effluent from the fish, is pumped through the grow beds. The grow beds are filled with gravel or clay balls. The plants convert the ammonia from the fish effluent into nitrates and the then filtered water is drained into sumps and pumped back to the fish. It’s a closed system and unlike aquaculture or hydroponics no water is wasted. There are at least two uses of the nutrients and the water.
Aquaponic systems are available through a couple of suppliers in Australia. Murray Hallam from Practical Aquaponics is one. He manufactures and sells several different systems. Murray first heard about Aquaponics from a fisherman in Western Australia.
“We were moaning about the lack of fish as fisherman do.”
It was also about the same time as the drought and Murray’s dam was dry. He couldn’t grow vegetables, something he found very disturbing. The fisherman started talking about growing his own fish. Murray was hooked.
Back then, 2005, there was very little information on the internet. Murray came across Joel Malcolm who was finishing his book, ‘Backyard Aquaponics.’
“I think I’ve got one of the very early copies, number three, read it from front to back and was inspired to start my own,” said Murray.
With a farming and a trade background Murray knew he could make it work in a practical sense. He started building systems for himself and other people and what started as a hobby became a business. I asked Murray about setting up an Aquaponic system including:
The systems are perfectly scalable, from a small system on your back patio that produces a few herbs and veggies, up to farm size. The system is expandable as long as you have the room. DIY can put together a modest system from recycled material that could provide two fish a week and a few vegetables for as little as $200 or $300 maximum.
The largest popular backyard kit is priced at $10,900 for a 3,000 litre system. From this system you can expect to harvest about 150 kilos of fish a year and about 700 or 800 kilos of veggies.
Pump size and cost will vary with each system. Comparative to the systems, the pumps are small. Power usage is minimal. A 3,000 litre kit costs approximately $180 per year for electricity. (SE Queensland prices)
Water and water chemistry
Rain water and dam water can be used to fill the fish tanks, as long as the water is healthy. If you use town water you need to rest it to evaporate the chlorine. The first 3-6 months of the system being set up requires vigilance until the system becomes balanced which means checking water PH, nitrates and ammonia at least daily. Chemistry kits are provided with most systems.
Where can it be placed?
The systems can be put out in the open but work better when under cover.
The native species that can be farmed include Murray cod, barramundi, sleepy cod, silver perch and jade perch. Murray knows people who are farming red claw and cray fish. Some fish don’t do well in tanks, yellow belly is one.
Where do I get the fish?
Hatcheries all over Australia have fingerlings of all the Australian natives (in season). You can buy them over the phone and they get sent by courier a couple of days later.
How big do the fish grow?
According to Murray there is a common myth that the fish only grow to tank size. He says Australian Native fish are different. They will grow as big as the food that is available to them. If you feed them well, over time, you will get fish that will grow to one or two kilos.
The fish can be fed on fish pellets or a more ‘organic and sustainable’ diet can be achieved by feeding black soldier fly lava or worms.
Fish are harvested at about 500 grams in weight and up. The quickest and most humane way to harvest is to give the fish a sharp blow to the back of the head. Once the fish is out their gills are cut.
What vegetables can I grow?
All leafy vegetables, fruits and herbs. There is a problem growing root crops. The gravel distorts the shape of the roots. Watering is automatic, so is the input of nutrients.
The downside of the system’s sustainability are the use of pumps. The cost for some people could be prohibitive with the inevitable rise in electricity costs. Solar panels could be a solution for the future.
Fish food is a matter of contention as fish pellets are made from by-catch out of the ocean. Murray believes that the industry is aware of this problem and says one of the solutions could be the use of carp as fish food. He is also setting up a two year study with a research scientist to investigate a ‘vegetarian’ diet for jade perch.
The big plus is the reduced use of water. Once the system is in balance the only water that is lost is through plant transpiration. There are also obvious health benefits as all the food you eat is fresh and organic.
Yandina Community Gardens, a non-profit organisation, located in Yandina on the Sunshine Coast has set up three Aquaponic systems after receiving funding from a federal government grant. The then president, Elisabeth Fekonia who teaches permaculture workshops at the garden, and was successful in securing the grant, said that the systems are a great example of one of the permaculture principles of bringing food production back to the city.
The fish are fed commercial fish pellets, supplemented with some lettuce from the grow beds. They are also given duck weed (Lemma minor). Tiny pieces are added to an ice cube tray and frozen. The frozen cubes are then given to the fish. As the ice melts the fish nibble the weed. Linda Mahony secretary of the organisation says this is a good way to control the weed, which could otherwise get out of control and clog up the system. Linda says the fish will be harvested at about 700 to 800 grams. She says if people don’t fancy the idea of eating the fish they can grow goldfish instead.
The vegetable beds are chock-a-block with amazing looking vegetables, including, celery, tomatoes, capsicum, beans, parsley, spring onions, eggplants, pak choy, basil, water spinach and lettuce.
“Spring onions grow brilliantly, probably too good,” says Linda. She says they are cut down to ground level and within six weeks are ready to harvest again.
The centre is investigating solar panels to provide power for the systems during the day and then using the power grid at night.
It has taken a while for the system to become balanced because at first, “ We were unsure of what we were doing,” said Linda but now its a breeze. Linda regularly attends the online Aquaponics forum for information.
 Earth Gardens Aquaponics
Malcolm J, ‘Backyard Aquaponics’
Video – Aquaponics Made Easy from www. Aquaponics.net.au
Forums: Aquaponics Made Easy by Murray Hallam. www.aquaponics.net.au/forum/
http://www.aquaponics.net.au/product/webcontent4.htm for list of all Hatcheries that supply fingerlings or email email@example.com and he will find a hatchery close by.