Otago University campus police are generally happy with the behaviour of students during orientation week and say outsiders are causing the issues.
There have been more arrests in Dunedin overnight, with orientation week well underway.
Four people were arrested after couches were set alight on Castle St, where around 150 students were partying.
Police say only two students are among the 12 arrests they've made since Saturday night, and they're seeing a growing number of non-students in the area.
"Unfortunately it is a time of the year where the students can get a little bit out of control, but generally they've been very well-behaved this year," says John Woodhouse, campus constable for Otago University.
"We're generally happy with the behaviour of the students."
He says police have tried to discourage fire-lighting and bottle-throwing.
"The culture has changed significantly from what it was in former years."
He says there's been a 30 percent year-on-year reduction in couch fires.
A number of problems were caused by non-students joining in, including high school students, unemployed people and people coming from outside Dunedin specifically for orientation week.
A 16-year-old was arrested over the weekend after allegedly threatening another man with a craft knife.
Police will be on high alert tonight as the annual toga party gets underway.