"ARI Smart Content - Integration - Fancybox" plugin provides ability to integrate fancybox with other applications like Media Gallery, Nivo Slider and others. The plugin can be enabled/disabled and configured on "Extensions → Plugin Manager" page on Joomla! backend. The plugin should be enabled if you want to ingrate fancybox with other other applications.
The plugin offers the same parameters as ARI Smart Content - Fancybox plugin.