What can I do if a tenant commits a breach in a fixed term tenancy?

If the tenant is in a fixed term tenancy and they breach their agreement, do we need to keep them until the end?

No matter whether tenants are on a fixed term or periodic tenancy, if they have breached the agreement there can be steps taken to resolve the issue, including eviction if needed.  The only difference is under a periodic tenancy a tenant can be given 90-days-notice-to-vacate without a reason given.  We feel if a tenancy has been unsatisfactory enough to terminate, the provisions of eviction under the Residential Tenancies Act are preferable to issuing a 90-day-notice-to-vacate.