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Denil fishway

Denil fishway

Denil fishway,  Pipeclay Creek, New South Wales Photo by Tim Marsden

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The Denil fishway was developed in 1909 by Belgian scientist G. Denil[2]. The Denil fishway does not create a series of separate pools, like many other fishway designs, instead it uses a series of symmetrical, closely-spaced, upstream-sloping, U-shaped baffles. These baffles turn the flow upon itself at the base of the baffle and create a low velocity zone that fish use to ascend.

There are currently no effective Denil fishways in Queensland. Denil fishways are widely used in North America and Europe, on barriers less than 4 m high and is often used in combination with a vertical slot fishway, for the passage of adult herring and salmon. This multi-structure approach is also being trialled in Australia (e.g. Murray River, New South Wales).

In Australia, research has indicated the potential of Denil fishways for native fish and this design has been applied to a few sites. The design tends to favour fish greater than 40 to 60 mm in length and the passage of bottom and midwater-dwelling fish species, with poor passage reported for surface-dwelling species such as mullet[1][4][3][5]. The main advantage of Denil fishways in Australia is that they can be built on steeper slopes than pool-type fishways such as the vertical slot design[4][5].


  1. ^ Baumgartner, LJ & NSW Department of Primary Industries (2006), 'A preliminary assessment of fish passage through a Denil fishway on the Edward River, Australia', Fisheries Research Report Series. [online], vol. 86, p. 24. Available at:
  2. ^ Denil, G (1909), Les échelles à poissons et leur application aux barrages de Meuse et d’Orthe, Brusels, Belgium.
  3. ^ Mallen-Cooper, M & Stuart, IG (5 January 2007), 'Optimising Denil fishways for passage of small and large fishes: Small and Large Fishes in Denil Fishways', Fisheries Management and Ecology. [online], vol. 14, no. 1, pp. 61-71. Available at: [Accessed 10 November 2020].
  4. ^ a b Marsden, T, Stewart, R, Woods, K, Ianna, S & Thorncraft, G (2006), Freshwater Fish Habitat Rehabilitation in the Mackay Whitsunday Region, p. 135.
  5. ^ a b 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) Denil fishway, WetlandInfo website, accessed 18 March 2024. Available at:

Queensland Government
WetlandInfo   —   Department of Environment, Science and Innovation