It seems a Pacu has a black hole in its stomach. I see him self serving at the fish feeder again and again until it is empty, without his hungry state being removed.
Steps to Reproduce
You need a Pacu, some water for it to live in (in my case polluted water at 2.7deg C) and a fully filled Fish feeder. watch.
This issue has been fixed in either a future version or updated in a previous version.