The P & O cruise ship Britannia was on the final leg of a cruise from Southampton in south-east England to the Norwegian fjords when the frakas erupted, ITV reported.
The passenger clothing has apparently upset some guests, Gaisford said.
"A witness from a group involved in the trouble Explained to the staff that things started when another passenger appeared disguised as a clown, "said Gaisford.
"This angered one of their groups for booking a cruise without a costume, which led to a violent confrontation."
In the UK means wearing costume.
"There was blood everywhere," wrote Gaisford. "Passengers used furniture and plates as weapons, and witnesses told me that they were so scared they had to hide when family groups were fighting," Gaisford added.
The police told ITV that three men and three women were attacked during the fight and that there were a number of injuries, including cuts and bruises.
Those involved in the bout were locked in their cabin for the final day of the cruise, ITV reported.
In a statement, a P & O Cruises spokesman told CNN on Sunday, "After Thursday night's incident on Britannia we can confirm that all guests left the ship yesterday and the matter is now in the hands of local police. "
He added that the cruise line does not tolerate disturbing behavior.