I currently have one cleaner shrimp and wanted to add another shrimp if possible. Are there any that would be okay to add and that won`t hide all of the time?
Another cleaner would give you a free live food source for your fish and corals every 2 weeks!
Otherwise, fire Shrimp should be OK in there... Never had one personally though so I can't say whether or not they hide out.
You can add another. Mine were added months apart and started makin babies by the next day. Just don't have odd numbers of cleaners otherwise they tend to get rid of the odd one out.