Gwent Police have launched an appeal after a fake Scottish £50 note was used at a takeaway in Maesycwmmer.
The incident is said to have happened on Thursday, April 4.
Officers would like to speak to the man pictured, as they believe he may be able to help with enquiries.
Police have asked the public and local businesses to keep an eye out for counterfeit money.
Anyone with information can contact the force on 101, quoting log 429 of 04/04/19.
Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.