With both prints and film, the intial water rinse gets rid of most of the fixer on the surface. After that, removing the remaining fixer is primarily a diffusion process, so soaking in several water changes with occasional agitation works very well.

As others have said, a non-hardening alkaline fixer will be easiest to remove. A slightly acidic non-hardening fixer will also wash out easily.

A residual fixer test can be perfomed to verify that your washing process is archival for the film or paper you are processing.
See: http://unblinkingeye.com/Articles/Ar.../archival.html