A man wielding a knife stole a taxi driver's coin holder after getting into a fight with the cabbie in East Perth on Friday night.
A police spokesman said a taxi driver was parked on Pier Street about 10.15pm when he was approached by a man who wanted to be taken into Perth.
"The taxi driver advised the man he was unable to take him as he already had a job, at which time the man produced a knife and demanded cash," the spokesman said.
"The offender entered the taxi and an altercation took place."
The taxi driver ran from his vehicle and the offender ran from the scene after stealing a coin holder.
The offender is described as having tanned skin, approx 183cm tall, with shoulder length brown curly hair and was unshaven at the time.
He was wearing a blue “Everlast” jumper and a cap.
Detectives would like to speak to the man pictured, who they believe may be able to assist with this investigation.
Anyone with information regarding this incident, or who recognises the man pictured is asked to call Crime Stoppers on 1800 333 000.