Harvesting Barramundi in Aquaponics

There’s nothing finer than to grow your own fish in your own backyard – except perhaps catching them and eating them! Sometime ago we decided to grow a few Barramundi in our aquaponics system. We were told that they were a specialized fish and unsuitable to grow-out for the beginner.


The Warm Water Fish

Now Barramundi do have some specific requirements. They are a warm water loving fish and thrive in water temperatures over 26 degrees Celsius where they tend to pile on the weight.  So if you live in the tropics then Barramundi are the way to go. The problem for us at Ecofilms living in a warm subtropical state of Queensland, Australia was that the fish were good to grow for half of the year but less so in the cooler winter temperatures when their growth slowed right down as they just rested around the bottom of the tank looking very lethargic.

We didn’t want to heat our tanks as that would be an expensive proposition. Anyone that runs aquaponics systems will tell you that during the winter months the vegetable grow beds radiate all warmth out of the system and into the heavens. So unless you have a passive solar green house and some method to heat the water, its best to stick to fish that enjoy your climate.

So we decided to test the conventional wisdom of the day and see if Barramundi would tolerate and survive the cooler winter temperatures where our water temperature would drop down to around 14 degrees C. Fattening them up in the warm summer months is the best method as they can lose condition over the winter as they slow right down at eating. Don’t be too concerned if your fish stop eating. Being cold blooded animals they can well tolerate not eating for a few weeks as their energy requirements to float in the water are not great.


Barramundi are carnivorous when small or more importantly – they can’t resist taking a chunk out of their little brothers and sisters. Our recommendation if to pay a little more and buy them when they are at least three or four inches long. This way your mortality rate will be less and you wont need to grade them into uniform sizes. In commercial aquaculture systems, barramundi are graded to remove smaller fish from each batch, lengthening their chance of survival.

We wanted to grow them in our small aquaponics system (A Murray Hallam designed Maximus System) with a bunch of Jade Perch fingerlings. As long as fish varieties are about the same size, we have found growing them together is not a problem. In fact we also have some catfish to clean up scraps from the bottom of the tank. All our fish get along just fine.

We found that the batch of barramundi we placed into our system slowed down the growth over winter as expected. They’d laze around the bottom at the back of the tank reflecting an eerie blue glow from their eyes. But we lost none over winter. All survived when the temperature plummeted. Sometimes it was hard to open the hatch and peer in. Especially on a cold day. Would they survive? Would there be any floaters?

They all did fine.

The following spring and into the summer these fish become a lot more active. They are a wonderful looking predator fish. They slap the water first when feed is introduced. Their Jade Perch cousins are more gentle and refined. Jades are a lot more inquisitive and will swim up to check the net you have placed into the water -ready to harvest your fish. The barramundi will eye you with suspicion.

Catching Them with a Net

Now catching your fish in a crowded tank with a net is guaranteed to end in mayhem if you don’t time it right. We’ve seen Murray Hallam lunge into the tank with a net and drag out half a dozen fish with one swoop. Thats one way to do it.

Our technique is to drop the net into the tank and just leave it sitting rigid and waiting.

Fish are sensitive and will freak out at sudden movements. We found they will quickly settle down if they notice after a minute or two that the net is stationary and not a threat. They will resume their normal swimming patterns. This is a good time to select the correct candidate. Resist the urge to suddenly strike wildly. Let the fish come to you. You’ve spend many months growing them so now enjoy the moment of catching them. We found the barramundi that we wanted to catch settle down and approach the net on a routine patrol. A quick wrist action and the fish is scooped swiftly into the net and lifted out of the water. This way we don’t damage the gills of a bunch of other fish if they are also caught and snared in the net. Remember fish are easily stressed and stress can kill fish.

This barramundi weighed in at 866 grams or just under 2lbs. From nose to tail just a tad under 400mm or 15 inches in length. A nice fish for Sunday dinner – with a whole heap of lettuce, tomatoes and cucumbers all grown in your own aquaponics system. The best thing is it has no muddy taste. No off-flavors.  Pure clean flaky white flesh.