New figures reveal hundreds of Corrections staff were assaulted by prisoners in 2017.
Department of Corrections data recorded 295 incidents between January and August last year.
Custodial Officer Neil Beales says three-quarters of the prison population have convictions for violence and there is no prison system in the world which is violence free.
"That is just not realistic to think we will reach that point. That doesn't stop us from zero tolerance and holding people to account when they do perpetrate violence against our staff or each other."
Mr Beales says violence starts before offenders even reach prison.
"We have to start dealing with the issues of family violence, bullying in schools, where people think they can walk along Queen Street in Auckland and kinghit people from behind because it's a dare from their mates," he says.
Mr Beales says around 1,400 extra staff have been employed since 2012.