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Trapezoidal fishway

Trapezoidal fishway – Key considerations

Trapezoidal fishway, Wyong River, New South Wales Photo by Tim Marsden

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In addition to the general information for all fishway types, the following applies to trapezoidal fishways.

Requirements for effective passage

Similar to vertical slot fishways, trapezoidal fishways are particularly useful in that they are relatively self-adjusting and maintain constant velocity and turbulence levels throughout the fishway at varying flows, and are therefore able to operate over a fairly wide range of headwater and tailwater levels[2].

Suitability and limitations

These fishways are relatively inexpensive and generally suitable for restoring fish passage where the head differential is <3 m. They are designed to safely enable the passage of small fish by producing low water velocities and turbulence[2].

Splash zones at the edges of the trapezoidal fishways may also facilitate the passage of climbing fishes such as elvers or cling gobies[1].

Precast-box culverts can be used to construct trapezoidal fishways[2].

Most debris appear to pass down the middle of the channel, reducing maintenance requirements compared to other fishway types[2].

Disclaimer: In addition to the standard disclaimer located at the bottom of the page, please note the Fishways (biopassage structures) disclaimer.


  1. ^ O'Connor, J, Stuart, I, Jones, M & Arthur Rylah Institute for Environmental Research (2017), Guidelines for the design, approval and construction of fishways. [online] Available at: [Accessed 25 February 2021].
  2. ^ a b c d 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) Trapezoidal fishway – Key considerations, WetlandInfo website, accessed 18 March 2024. Available at:

Queensland Government
WetlandInfo   —   Department of Environment, Science and Innovation