A man suffered injuries to his face and body after being attacked in a pub toilet.
The assualt took place in the gents at The Rainbow, on Lower Warrengate, on Saturday, July 27.
Police said pub customers broke up the fight, and might be able to help them with their enquiries.
The suspect was in his 30s, and about 6ft 7ins tall.
He was very muscular and had short, light-coloured hair.
Anyone with any information should contact 101, quoting 13130312453, or Crimestoppers on 0800 555 111.