Worsening levels of drugs and violence inside HMP Elmley have been exposed by a snap inspection which has caused concern about conditions inside the jail.
Staff shortages have been blamed for the situation in the prison which also has overcrowding issues, with 1,252 men locked up in the 985 capacity facility on the Isle of Sheppey in Kent.
Fights between inmates have leapt by 60% in the past year, HM Inspectorate of Prisons found.
So intimidating is the atmosphere in parts of the prison that some of the men purposely try to get themselves locked up in isolation for safety reasons.
Meanwhile, drugs are rife with a synthetic form of cannabis known as Spice particularly abundant.
Understaffing is a factor too, with a cut in staffing levels at Elmley and two neighbouring prisons from 740 to 340 since 2010.
The disturbing findings at HMP Elmley sparked a call for the prison to be "stabilised" by chief inspector of prisons, Nick Hardwick.
Extra staff are being hired to address the problem, said Michael Spurr, chief executive of the National Offender Management Service.
"When the inspectorate visited Elmley in June the prison was operating with a high level of staff vacancies.
"Permanent recruitment is under way."