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