Just after midnight, the water was still over twenty degrees during the day, and the river runs so calm you can hear the ripple against your own rod tip. On nights like this, when the air smells of warm mud and willow leaves, I pull the classic surface float completely out of the game and switch to something most catfish anglers massively underrate. The underwater float — what I simply call the U-float — is, for me, the tool that makes the difference between a quiet watching session and a full-on catfish battle during these last warm weeks of summer.
Why the Surface Float Hits Its Limits on Calm Nights
A normal surface float gives itself away. It rocks in the wake of passing boats, dances with every gust of wind, and on clear, still nights it even casts a shadow under a full moon that makes wary catfish suspicious. Exactly when the water lies flat as glass and the big fish approach the bait with extra caution, a surface float keeps producing small, false movements. I used to stare at a twitch for hours, only to find out it was a current eddy or a drifting leaf. That costs nerves — and worse, it costs bites, because a suspicious catfish often lets go of the bait again before anything is even visible on the surface.
The Underwater Float: Invisible Beneath the Surface
The underwater float solves exactly this problem by staying completely submerged. It runs free on the mainline and is set to the desired depth with a stop knot, usually somewhere between one and a half and three metres below the surface, depending on how deep the channel is at my spot. The bait hangs beneath it on the leader, the lead sits below the float, and together they hold the whole rig stable in the water without wind or waves throwing it off. A take transmits directly, with no detour, through the taut line straight to the rod tip or the bite alarm on the bank. The signal comes through clean and hard the moment the catfish takes the bait and moves off, without the usual hesitation and blur that a restless surface otherwise causes.
For the rig itself, I use braided mainline of at least 0.35 to 0.40 millimetres, a short leader of hard mono or Amnesia around 80 to 100 centimetres long, and a catfish hook in size 6/0 to 8/0, depending on the bait. I pick the underwater float's buoyancy to match the combined weight of bait and lead — usually somewhere between 40 and 80 grams — so it sits cleanly even in light current instead of constantly getting pulled upward.
The Lobworm Bundle: My Bait for Warm Nights
When water temperature climbs above twenty degrees in high summer, wels catfish get more active and far less picky than many anglers assume. That's exactly when I reach for a lobworm bundle, because it's cheap, quick to get hold of, and surprisingly effective. I thread ten to fourteen fat lobworms onto the hook one after another until they form a thick, worm-like clump that keeps wriggling for minutes and steadily releases scent into the water. That combination of movement and smell is practically irresistible to a catfish, especially on nights when the water carries a bit of colour and the fish is hunting more by smell than by sight.
To stop the bundle falling apart on the cast, I also slide a thin rubber band over the head end of the worms, right below the hook eye. That holds everything together without restricting the worms' natural movement too much. If you want it even more robust, you can use a baiting needle and thread the worms onto a short length of thread before tying the whole strand to the hook. What matters most to me is using fresh, lively worms — dead or mushy lobworms lose their appeal fast and slip off the hook far too soon.
Drift Fishing: Covering Long Stretches of River at Night
In the warm summer months, wels catfish spread out much more widely through the river than they do in spring or autumn. Instead of concentrating only in the deepest channels, they patrol at night along shallower edges, sandbars, under overhanging trees, and even over open gravel bars, as long as there's enough small fish and crayfish activity there. That's exactly why I lean heavily on drift fishing on these nights, to cover longer stretches at once instead of sitting rigidly in a single spot.
I let the underwater float rig, weighted very lightly, drift slowly with the current on purpose, often over a distance of fifty to eighty metres before reeling in and recasting. The float keeps the bait at a constant depth despite the drift, instead of rising to the surface or sinking uncontrollably to the bottom. Fishing from a fixed spot on the bank, I usually run two to three rods at once, each set to a slightly different distance and depth, so that over the course of one night I effectively work through an entire stretch of river systematically. Anglers fishing from a boat can steer the drift even more precisely, holding the boat gently against the current and guiding the baits at a tightly controlled pace over promising spots.
On the Water: Patience, Gear, and the Right Moment
For this style of fishing I need rods with real backbone, at least 2.7 kilograms of casting weight, paired with a sturdy freespool reel that holds enough line for long runs. The bite alarm should be set sensitively enough to register even a cautious first pick-up, because with the lobworm bundle presentation especially, some catfish take the bait hesitantly at first before committing fully. In those moments I deliberately wait until the line is genuinely running before I strike, rather than hitting the first twitch.
The calmest, warmest nights of late summer are often more productive for me than stormy nights with thunder, because the fish hunt more relaxed and the underwater float can play out its full advantage over a visible surface float. If you catch one of the last truly warm nights on the river in the coming weeks, definitely try the combination of underwater float, lobworm bundle, and a clean drift before the water cools noticeably and the fish's behaviour shifts again.
My Verdict
On warm, calm nights, the underwater float is, for me, the superior choice over any surface rig, because it stays invisible and transmits bites razor-sharp. Paired with a fresh lobworm bundle and a deliberately slow drift, you can fish long stretches of river effectively — especially once wels catfish spread out widely through the water in high summer. Try this combination on one of the next mild nights, and give the rig time before you recast.