Barra, basil and bok choy – how aquaponics is providing a tasty harvest at CDU
Charles Darwin University (CDU) aquaculture trainer Morris Pizzutto knows a thing or two when it comes to fish and plants, so it’s no surprise that he has plenty of fresh, organic herbs, fruits, and vegetables for Casuarina campus staff to take home thanks to a clever filtration system.
Mr Pizzutto looks after barramundi in large tanks to show his students the practical tasks in aquaculture, but knew he needed an effective way to filter out waste products from the water.
So the aquaculture team rigged up a closed loop aquaponic system, a filtration process which cleans the water and provides nutrients to the plants.
The produce grown includes bok choy, basil, mushroom plant (also known as rungia), Chinese cabbage, tatsoi, basil, tomatoes, kangkung, mint, and spring onions.
"By using waste products from fish to grow plants, we’re able to create a growing system that saves water and maximizes efficiency. It is well suited to the Darwin climate where it is challenging to grow in soils” Mr Pizzuto said.
"The waste products from the fish build up nitrates in the water, which are typically kept in check by doing water changes. However, these nitrates are perfect for nourishing our plants."
Overflow from tanks travels through a set of pipes which lead to planter boxes filled with sand and soil.
The water then filters through the sand, removing excess nitrates before flowing into a catchment area and returning to the tank.
This system ensures minimal waste and optimal use of resources.
"The sand bed filter aerates the water and ensures it’s clean when it cycles back to the pond," he said.
"This is just one type of small-scale, circular system that exemplifies how we can sustainably manage resources.
“Growing food at home using this method works very well if you understand how to make a few simple water adjustments. We run a short two-day course every term at CDU which is currently delivered for free.”
The plants are cultivated without pesticides and chosen based on seasonal suitability to ensure the best growth – due to this approach, they are fresher and last longer than produce brought at the store.
When they are ready to be picked, Mr Pizzutto is happy to share around.
As for the barramundi, they are delivered to TAFE culinary students so they can learn how to plate up delicious seafood dishes at CDU’s Karawa restaurant at the Palmerston campus.
Course enquires can be made by contacting CDU Environmental studies at ahc@cdu.edu.au.