An 61-year-old passenger has been left with a broken leg after an "altercation" on a Rainbow One bus.
The Trent Barton run bus links Nottingham with Alfreton, Ripley, Eastwood and Heanor.
Nottinghamshire Police detectives have released an image of a man they want to speak to after the incident on the Rainbow One bus as it stopped in Upper Parliament Street, Nottingham.
It happened at around 11pm on Saturday, September 29, 2018.
A police spokesman said: "If you recognise him or think you can help, please contact us on 101 quoting incident 136 of 29 September. You can also call Crimestoppers anonymously on 0800 555 111. "