Displayrelated post by taxonomy tag

taxonomy_tags.php

<?php
// Get taxonomy tags
$taxonomy = 'photo-tag';
$terms = get_terms($taxonomy);
shuffle($terms);
if ($terms) {
  foreach($terms as $term) {
   	$tags = $term->slug;
  }
}

$args = array(
				'post_type' 		  => 'photo',
				'post_status' 		=> 'publish',
				'photo-tag' 		  => $tags, // display by tag
				'orderby' 			  => 'rand',
				'post__not_in' 		=> array( get_the_ID() ),
				'posts_per_page' 	=> 6
			);

// etc ...

?>