Crafting a shim rig baited for Australian catfish

Few pursuits feel more rewarding than tempting a hard-pulling catfish out of a tannin-stained river at dusk, and the technique of leading a bait on a shim has long been a quiet favourite among northern New South Wales and southern Queensland anglers. A shim is a slim, slightly curved metal lure that flutters and rolls with the slightest current, and when paired with a strip of fresh bait it becomes a hybrid presentation that drifts past the nose of a wary eel-tailed catfish without looking like anything artificial. The idea is simple: let the shim do its wobbling work to draw attention, while the bait leaves a scent trail that closes the deal. Learn more about Read.

Australian catfish are not the channel monsters of the American South, but our native tandan, eel-tailed catfish and the introduced species found in places like the Brisbane River still respond aggressively to a moving bait that smells right. Working out how to make and lead this rig properly is mostly about matching the size of your shim to the water you fish, picking bait that is legal and available where you cast, and remembering that our waterways, from the tidal reaches of the Mary to the slow bends of the Darling, each demand a slightly different lead.

What a shim actually does in the water

A shim is essentially a thin slice of metal with a gentle arc, designed to fall slowly through the water column while wobbling side to side. That erratic fall mimics a wounded baitfish, which is exactly the silhouette a hunting catfish locks onto before it investigates with its barbels. In clearer systems like the upper Brisbane or around the rock walls of Lake Wivenhoe, the flash from a chrome shim can travel a fair distance, making it useful as a search lure. In dirtier water such as the lower Murray after a fresh, scale matters less and scent matters more, so the shim becomes a delivery vehicle for whatever you impale on the hook.

Most anglers fishing the Australian market pick shims between 20 and 40 grams. Anything lighter struggles to stay in the strike zone when there is current; anything heavier drops past the fish too quickly. A brass or polished stainless shim holds up well against the abrasive jaws of catfish and the inevitable grumbling over rough structure.

Picking bait that suits the local larder

Bait choice is where the rig really comes alive, and what you can buy at the local tackle shop is not always what you can legally use. In Queensland, for example, regulations prohibit the use of certain live freshwater fish as bait, while in New South Wales and Victoria you need to check the current freshwater fishing rules before collecting your own. Fresh is always better than frozen, and strong-smelling options tend to produce faster bites.

Common productive choices across the eastern states include:

• Yabby tails, peeled and trimmed to the size of a small cigar
• Mullet strips cut from a freshly caught poddy mullet
• Chicken gut or liver when fishing for larger eel-tailed catfish in the Murray-Darling system
• Prawn heads or whole school prawns bought from a Brisbane or Sydney fish market

Avoid oily fish like sardines if you are targeting tandan, as the scent can attract smaller nuisance species before a catfish finds the offering.

Step-by-step build of the baited shim rig

The rig itself is straightforward, but the order in which you assemble it matters. Start with a short, stiff leader of around 40 centimetres in 30 to 40 pound fluorocarbon, because catfish have rough mouths and will fray light line against their pectoral spines. Tie a size 1/0 to 3/0 baitholder hook depending on the profile of your bait, and finish with a small barrel swivel to attach to your mainline.

Slide the shim onto the leader above the hook, allowing it to move freely. This is where many beginners go wrong: the shim should sit roughly 15 to 25 centimetres above the hook so it wobbles independently and does not mask the action of the bait below. Add a small split shot about 30 centimetres above the shim if you need extra casting weight or to hold the rig in a slower drift. When you thread the bait onto the hook, leave it hanging naturally, as a stiff bait will spin rather than flutter.

Reading the water and timing the drift

Catfish in Australia are most active in low light, so dawn and dusk sessions tend to produce more strikes than the middle of the day. Look for the edges of structure where a current seam meets slack water, such as the inside of a river bend or the downstream side of a submerged log. On tidal stretches like those around the upper reaches of the Brisbane River near Bremer, fish the last two hours of the rising tide when catfish push into the shallows to feed.

Cast the rig slightly upstream of where you expect the fish, let the current carry the shim and bait along the seam, then retrieve slowly with the occasional pause. The pause is critical, because a shim sinks and wobbles on the drop, and a catfish will often take the bait as it settles. If you feel weight during the pause, lift steadily rather than strike hard, as catfish hook themselves once they commit.

Local rules worth checking before you go

Australian fishing rules change regularly and vary between states, so it pays to check the relevant authority before a session. In New South Wales, a recreational freshwater licence is required for most river fishing, while in Queensland the rules differ for tidal versus freshwater waters and there are specific protections around using certain species as bait. The Victorian system recognises a single recreational licence that covers most inland waters, though some trout streams prohibit bait entirely. Size and bag limits apply to catfish in each jurisdiction, and there are closed seasons in some parts of the Murray-Darling basin to protect native stocks during spawning. A quick call to your local fisheries office or a look at the current DPI website saves the embarrassment of a fine on the bank.

Adapting the rig to Australian conditions

One of the advantages of a baited shim rig is how easily it travels. For a weekend trip out of Melbourne to the Goulburn, the rig packs down to almost nothing in a small tackle tray, and the same setup works just as well on a cast from a tinny on the Fitzroy. If you are fishing from shore along the urban stretches of the Brisbane River, scale down to a lighter 20 gram shim and a smaller hook, because the catfish in those reaches are often juveniles and bait-stealing eels will test heavier gear.

Adjusting sinker weight is usually the only change needed when moving between venues. A heavier split shot keeps the rig down in a fast-flowing river like the Severn, while on a still impoundment like Lake Mulwala you can often run the shim with no weight at all and let it work the upper water column. Pay attention to how the shim falls on the initial drop after each cast, as that falling flutter is what draws the catfish in from a distance.

Field-tested mistakes worth avoiding

Even experienced anglers slip up on this rig, and a few patterns repeat themselves across the banks. Tying the shim too close to the hook kills its independent action, and the bait ends up looking like an awkward lump rather than a separate offering. Overloading the hook with a chunk of bait large enough to feed two catfish makes it hard for them to suck the hook in, and many bites turn into disappointing pecks that never quite connect.

Using too stiff a leader in clear water will spook wary fish, especially on bright sunny days at Lake Wivenhoe or the upper Brisbane, so scaling down to 20 pound fluorocarbon is often worth the trade-off in abrasion resistance. Finally, forgetting to check the hook point after every few fish is a common lapse, because a catfish's bony jaw plate can dull even a chemically sharpened hook and leave you wondering why the strikes stopped.

A baited shim rig does not replace a well-presented static bait, but it covers more water, attracts fish from further away, and turns a quiet session into something far more active. Match the shim weight to the current, keep the bait fresh and local, and respect the licence rules wherever you cast. The memory that tends to stick is the first time a deep, slow pull bends the rod over and you realise the shim has done its job and the bait has closed the gap.