A TOOWOOMBA bouncer and gym owner who punched a woman in the face at a city hotel has been fined $2500 but escaped having a conviction recorded.

James Saia Turepu Vailahi pleaded guilty before Toowoomba Magistrates Court to assault occasioning bodily harm arising from the incident at The Office in Duggan St on the night of February 7.

Police prosecutor Julia Wheaton told the court the incident arose from some push and shove between members of two groups of people in the bar about 2.05am. During the melee, one of Vailahi's friends and the boyfriend of the 21-year-old woman victim had engaged in an altercation and she had stepped in between them.

However, as the altercation continued she had been pushed by someone and had struck Vailahi who turned and punched her once to the face knocking her backwards onto the floor.

He had then left with a friend in a taxi.

Senior Constable Wheaton said the victim woman was left with a swollen lip and cuts inside her upper and bottom lips.

Spoken to by police two days later and shown CCTV footage of the incident, Vailahi told officers he had reacted after being "dog punched", Snr Const. Wheaton said.

However, the 25-year-old's solicitor Claire Graham said her client was unaware at first that the person he had struck was a woman.

Her client had been out that night celebrating his brother's 21st birthday and though he didn't drink much he had had eight vodka drinks in the lead-up to the incident, she said.

The New Zealand born Vailahi had no previous criminal history at all and the incident had impacted on him significantly with his business partner moving on as a result and he had suffered some backlash on Facebook.

Her client's security officer licence had also been suspended as a result of the incident, Ms Graham told the court.

Ms Graham submitted the victim's injuries were relatively minor.

Her client was the director of two companies and had no previous convictions and asked that no conviction recorded.

Magistrate Graham Lee said he accepted the assault was out of character for Vailahi but that he had struck a woman who had sustained some injury.

"Offences of violence are very serious and there are cases where people have been jailed for a first offence of violence," he said.

Without recording a conviction, Mr Lee fined Vailahi $2500 for the assault and a further $300 for failing to register his identifying particulars with police within seven days of being charged.