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Vertical slot fishway

Vertical slot fishway

Vertical slot fishway examples: </br>
		1. Left: keyhole slot design in a vertical slot fishway, Yallakool Creek, New South Wales </br>
		2. Middle: precast concrete rectangular vertical slot baffle, showing rocky base of fishway and metal grate overhead, Yallakool Creek, New South Wales </br>
		3. Top-right: vertical slot fishway, showing rectangular slot design, Sheepstation Creek, Ayr, Queensland </br>
		4. Bottom-right: metal keyhole slot design in vertical slot fishway baffle, Chowilla Regulator, South Australia
		Photo by Ivor Stuart (1,2 and 4), and Tim Marsden (3)

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Loudoun Weir, Condamine River, Queensland showing vertical slot fishway entrance (left), and gravel accumulation over trapezoidal fishway in front of low flow fishway entrance Photo by Douglas HardingVertical slot fishways are generally used on low- and medium-sized weirs up to 6 m high. They consist of a concrete channel structure divided into individual pools, each connected by a baffle with a vertical gap or slot. The vertical slot runs the full depth of the baffle and angles water flow across the pool to the opposite side, thereby dissipating the energy of the water in each pool. Long vertical slot fishways may have resting pools to allow fish to rest during ascent[1].


There are three main sub-types of vertical slot fishways, based on the shape or shapes of the gap or slot in the baffles:

  • standard vertical slot fishways have a long rectangular shaped slot
  • keyhole slot fishways have variable slot width and shape. They typically have a wider slot at the bottom (e.g. 0.35 m) than at the top (e.g. 0.15 m), allowing a single fishway to pass small- and large-bodied fish by decreasing turbulence and without increasing pool size
  • dual vertical slot fishways have more than one type of slot, i.e. a combination of standard vertical and keyhole.


  1. ^ O’Connor, J, Stuart, I & Mallen-Cooper, M (2015), 'Performance, operation and maintenance guidelines for fishways and fish passage works', Trove. [online] Available at: [Accessed 10 November 2020].

Last updated: 10 May 2021

This page should be cited as:

Department of Environment, Science and Innovation, Queensland (2021) Vertical slot fishway, WetlandInfo website, accessed 18 March 2024. Available at:

Queensland Government
WetlandInfo   —   Department of Environment, Science and Innovation