Below the high country the Murray is a lowland river held up by weirs. The water between the walls is slow and deep, and the fish sit on structure: fallen timber, undercut banks, the outside of bends where the current has scoured a hole. The gradient chart shows how quickly the river drops out of its steep upper country and then runs nearly flat for most of its length, and the bank cover chart shows how much of the river’s edge is still vegetated.

In our read, cod treat a big snag in a slow pool as home, and golden perch hang around the same timber but roam more. The steep upper river is a different animal: faster, colder water with riffles and runs, where trout take the usual stations at the heads of pools and along the seams.

Murray cod and golden perch are the main event. Silver perch, freshwater catfish, redfin and carp are all recorded, as are trout cod, which look a lot like a small Murray cod. Learn to tell them apart and check the current guide for their status before you keep anything. Brown and rainbow trout are recorded too, and river blackfish.

The small fish the predators eat are recorded here as well: Australian smelt, carp gudgeons, bony bream, rainbowfish and several galaxias, plus Murray crayfish. That menu tells you what to throw. A big, bulky fly that moves water suits a cod looking for a bony bream or a crayfish, and a smaller baitfish pattern suits golden perch and redfin.

NSW recreational fishing trust money has gone into tagging studies of how cod use the upper Murray, so the fish up there are being watched as well as fished.

Summer and early autumn are the obvious time on the lowland water. In our experience the warm months are when cod and golden perch are most active in shallow water and most willing to chase a fly, and the NSW guide suggests the river around Mulwala when the lake is busy over the summer school holidays. In our experience the edges of the day matter more than the month: first light, last light and the first hour of dark.

Winter cod fishing is slower but not dead. Fish deeper and slower and expect fewer takes. Check the current NSW and Victorian guides for any seasonal closure on your stretch before you plan a spring trip.

The flow and hydro-thermal charts come from a gauge high in the upper river, above Hume Weir. They give you the shape of the year in the high country, but they cannot show what Hume releases or how the lowland river is running. In our read, the warmer months bring terrestrials such as hoppers onto the grassy banks up there.

For cod, use a heavy rod (an 8 to 10 weight), a sinking or intermediate line, and a short, stout leader. Throw a big fly tight to timber and bring it back slowly, with pauses. Most takes come close to the snag, so be ready to turn the fish before it gets back in. After dark, a large surface fly worked slowly along a snag-lined bank is a good bet.

For golden perch and redfin, drop to a 6 or 7 weight and fish a smaller weighted fly, something like a Woolly Bugger in dark or olive, slowly along the same timber.

On the trout water, fish it as you would any small mountain river: nymphs under an indicator in the runs, a dry or a hopper along the banks in summer, and an approach from downstream.

The access card lists the NSW angler access sites and boat ramps along the river. Treat them as places to get to the water, not as permission to cross private land. Where you are not sure whose ground you are on, ask.

As on any big lowland river, snags and steep, slippery banks are the everyday hazard. Wear a life jacket in a boat, and keep well clear of the rough water right below any weir. Check the live conditions for the gauge nearest you before you go, because the level can change from one trip to the next.

Check the current guides, including their closed-waters lists, for the stretch you plan to fish. The river borders three states, so before you fish, read the current NSW Department of Primary Industries and Regional Development, Victorian Fisheries Authority and Primary Industries and Regions SA fishing guides for the stretch and the bank you will be on. That covers bag and size limits, the cod and trout seasons, and anything that applies near the weirs and locks.