In the rich text editor:
@lovefish
In a comment:
[lovefish](https://chowlings.com/user/lovefish)
For Names and Avatars:
In the rich text editor:
%lovefish
In a comment:
[![lovefish's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/lovefish) [lovefish](https://chowlings.com/user/lovefish)