Between 11am and 1pm on Saturday 6 February, a man was walking along the Canal Path, near to the lock after Park Street, when he saw a two people walking towards him.
The man warned them about mud on the path then one of them punched and kicked him, causing him to fall into the ditch.
The two individuals then walked off towards the town centre.
Two members of the public stopped to help the victim up and then continued on their walk.
The victim sustained bruising and swelling to his leg and hand. He did not require hospital treatment.
The offender is described as a male in his late teens, approximately 5ft 5ins tall with short mousey brown hair. He was wearing a green Stone Island jacket, blue jeans and trainers.
Officers are keen to hear from anyone who may have witnessed this incident or has any information that could help with the investigation. They are particularly keen to hear from the couple who stopped to help the victim as they may have vital information.
You can get in touch using our online form or by calling 101, quoting reference number 43210052512. Alternatively, you can contact the independent charity Crimestoppers anonymously via their website or on 0800 555 111.