Yes, this is possible in vanilla FishEye if your instance administrator enabled watches for particular repository, see https://confluence.atlassian.com/display/FISHEYE/Browsing+through+a+repository#Browsingthrougharepository-Watchingarepository.
In order to watch activity in particular repository or any folder or that repository open this repository/folder in FishEye (e.g. https://fisheye2.atlassian.com/browse/ehcache/trunk/ehcache/ehcache-core/src/main/java/net/sf/ehcache), then click on the Tools cog in the top right corner and select "Watch" option. Note you need to be logged in to see this option.
If you want to watch particular file only, go to activity stream of selected repository folder and click "Filter commits" to filter for example only files of particular name. Then again click Tools cog and select Watch to add watch for your filter.
You can later review and manage your watches by selecting Profile Settings / Watches.
Hope that helps,
Atlassian's marketplace partners have had a very productive start to 2021! Since our last roundup, our developer community has added over 160 new cloud apps to the Atlassian Marketplace to help you...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events