From the wiki page linked above: 15 February 1798 Federalist Congressman Roger Griswold of Connecticut attacked Democratic-Republican Party Representative Matthew Lyon of Vermont with a hickory walking stick in the chambers of the United States House of Representatives. Griswold struck Lyon repeatedly about the head, shoulders, and arms while Lyon attempted to shield himself from the blows. Lyon then turned and ran to the fireplace, took up a pair of metal tongs, and, having armed himself thus, returned to the engagement. Griswold then tripped Lyon and struck him in the face while he lay on the ground, at which point the two were separated. After a break of several minutes, however, Lyon unexpectedly pursued Griswold again with the tongs, and the brawl was re-ignited.
The two men had a prior history of conflict. On 30 January of that year, Griswold had publicly insulted Lyon by calling him a coward, and Lyon had retaliated by spitting in Griswold's face. As a result of Lyon's actions in that case, he became the first Congressman to have charges filed against him with that body's ethics committee, although he escaped censure through a vote in the House. 
IMHO, the funniest one: 5 February 1858
Congressman Laurence M. Keitt of South Carolina ..... Keitt became offended when Pennsylvania Congressman (and later Speaker of the House) Galusha A. Grow stepped over to the Democratic side of the House chamber while delivering an anti-slavery speech. Keitt dismissively interrupted Grow's speech to demand he sit down, calling him a "black Republican puppy". Grow indignantly responded by telling Keitt that "No negro-driver shall crack his whip over me". Keitt became enraged and went for Grow's throat, shouting that he would "choke him for that". A large brawl involving approximately 50 representatives erupted on the House floor, ending only when a missed punch from Rep. Cadwallader Washburn of Wisconsin upended the hairpiece of Rep. William Barksdale of Mississippi. The embarrassed Barksdale accidentally replaced the wig backward, causing both sides to laugh spontaneously. Keitt would later die of wounds following the Battle of Cold Harbor while fighting for the Confederacy.
Lots more, but this one takes the cake: 24 February 1887
The Indiana General Assembly experienced a massive brawl between Democrats and Republicans in the Indiana Senate and Indiana House of Representatives...
...... he was attacked, beaten, and thrown bodily from the chamber by the Democrats, who then locked the chamber door, beginning four hours of intermittent mass brawling that spread throughout the Indiana Statehouse. The fight ended only after Republicans and Democrats started brandishing pistols and threatening to kill each other. The Governor deployed the Indianapolis Police Department to restore order. Subsequently, the Republican-controlled House of Representatives refused to communicate with the Democratic Senate, ending the legislative session and leading to calls for United States Senators to be elected by popular vote.
