MP Eric Joyce has vowed to confront his issues with "alcohol and a tendency towards being aggressive physically" after being spared jail for assault.
Joyce, MP for Falkirk, was arrested after a brawl in the Strangers' Bar in Westminster in which he headbutted Conservative MP Stuart Andrew.
Labour whip Phil Wilson and Tory councillors Luke Mackenzie and Ben Maney were also punched in the brawl. A witness said the brawl was "like the wild west".
Joyce pleaded guilty at Westminster magistrates court to four counts of assault. He was fined £3,000 and banned from pubs for three months.
Outside court he apologised to his victims and admitted he was lucky to escape a custodial sentence.
He said the fight was a "matter of considerable personal shame" and that the punishment was fair.
"Drink was an aggravating factor, there's no question about that," he said.
"It's something I have to deal with personally. Not everyone who drinks gets involved in fights and certainly when they are my age."
Joyce, 51, of Bo'ness, was suspended from the Labour party after he was arrested. He is expected to be expelled once disciplinary proceedings are completed.
He had said he would step down at the next general election but would continue as an MP in the meantime.
"I was elected until 2015 and I will certainly serve until then," he said.
Joyce will also pay £1,400 compensation to his victims. He said that the fight on 22 February, which saw him restrained by four security officers and a bar window broken, was not a good representation of the levels of drinking in the House of Commons.
"I have to reflect on the best way of dealing with both alcohol and a tendency towards being aggressive physically - I have to do something about that myself," he said.
Joyce has been MP for Falkirk since 2000 and served in the Army Education Corps before taking on a career in politics.