Barra are tropical fish, and they react to temperature in two directions. When it is too warm, they leave an area in search of somewhere more comfortable. When it is too cold, they head for warmer water. Either way, the temperature is moving them.
The commonly quoted ideal feeding range for barra is a water temperature of about 26 to 32 degrees. They will feed lower than that, down to the high teens, and they will feed a lot warmer too. We have caught them in very hot water in a shallow tidal creek after a long dry spell in the wet season — though we doubt they stay in water like that for long.
Too cold: the dry season snaps
Through the dry season, cold south-easterlies push north off the desert into the Top End, and the barra feel it. The first cold snap — often around the middle of May — has the biggest effect.
In our experience it is the change in temperature, more than the temperature itself, that shuts fish down. After a sudden drop they go doggo for a day or two, much like we head for the jumpers and do not want to go outside. Once they are used to it, they are more sluggish, but they still have to eat.
When it is cold, look for the warmest water you can find:
- Shallow bays with weed beds that the sun warms through the day
- The downwind side of a billabong or lake, where the warmer surface water has been blown against the bank
Why the morning run-out goes quiet
This is one to keep in mind for the dry season. On neap tides from around May to September, the night-time high tide pushes up over mud banks that have cooled overnight, and the water up in the river can come back a degree or two colder.
The next morning's run-out is likely to be slow. But as the mud banks are exposed and warmed by the sun, then the tide turns and creeps slowly back over that warm mud, the water temperature rises enough to switch the barra back on. We have seen it many times, and the smaller systems that drain right out — the ones that behave like big coastal creeks — show it most clearly.
Pay attention to the water temperature as you drive to a spot. If it is a degree or two warmer out the front than up the creek, the fish up inside may be doughy until the warmer water pushes back in on the incoming. That incoming can fish very well — sitting on one side of the river and casting across, just as you would in any coastal creek.
This effect is strongest on the neaps. On the springs the temperature still changes, but the water rushes in too fast to give you that long, steady bite as the fish mooch their way up with the warmth.
The midday billabong bite
In the fresh, the same thing can produce a bite at a time of day we do not normally associate with barra. In the billabongs in May and June, fish that have dropped deep in the cold will move up onto a steep, sun-warmed bank with a lily line once the sun has been on it for a while — and switch on in the middle of the day.
Too hot: the build-up
At the other end of the year, it works in reverse. On a hot afternoon in October or November, bait in the shallow back of a billabong bay gets too warm and heads out to the deeper water. That can switch the barra on right in the heat of the day, when most people have gone home. If you are prepared to start later and fish into the afternoon at that time of year, it can be well worth it — and those same spots can hold fish into the evening.
In the wet, a stretch without rain can heat the shallow water up the top of a system until the bait leaves it for cooler water. A big tide pushing cooler water back up into the creek mouths can trigger a hot little session as the bait comes out.
Hot drains in the harbour
On a hot build-up day, harbour drains can go off the bite as the water draining off sun-baked banks gets too warm. The fish tend to sit off the front of the drains, in deeper, cooler water.
So stand off further than you normally would. Instead of pulling up a cast's length from the mouth of the drain, start a cast and a half or two casts away, and give everyone half a dozen casts before you move into the shallows. You will spook fewer of them.
Warm is not always bad
Water in the mid-thirties is what barra expect in the build-up, especially at the mouths of the big rivers as warm tides push in and lift the average temperature of the whole system. If the fish are there, they are used to it and they still have to feed. It is the sudden swings, not the steady heat, that you need to plan around.
Common questions
What water temperature do barramundi prefer?
The commonly quoted ideal feeding range is about 26 to 32 degrees. They will still feed in cooler water down to the high teens, and in the build-up they routinely feed in water in the mid-thirties.
Why does barra fishing go quiet after a cold snap?
It is mainly the sudden change in temperature that shuts them down. After the first cold snaps of the dry season, barra go quiet for a day or two until they adjust. Look for warmer water, such as sun-warmed shallow weedy bays or the downwind side of a billabong.
Why is the morning run-out tide slow in the dry season?
On neap tides, the overnight high pushes over mud banks that have cooled in the night, so the water draining out in the morning is a degree or two colder. Once the exposed mud has warmed in the sun and the incoming tide creeps back over it, the water warms up and the bite often switches on.
Can hot weather stop barra biting?
Yes. On hot build-up days, water draining off sun-baked banks can get too warm, and barra sit off the front of harbour drains in deeper, cooler water. Start a cast and a half or two casts back from where you normally would, and work in slowly.
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