In the rich text editor:
@sugarfish
In a comment:
[sugarfish](https://chowlings.com/user/sugarfish)
For Names and Avatars:
In the rich text editor:
%sugarfish
In a comment:
[![sugarfish's Avatar](https://chowlings.com/images/avatars/531.png?v=1644063304)](https://chowlings.com/user/sugarfish) [sugarfish](https://chowlings.com/user/sugarfish)