Right from the Snapcraft rules it states:
Regarding AFK Farming
If we can prove your focus is not in-game while you are performing game-related action (literally anything except being completely afk), we will consider you bannable. Our methods will include messaging, teleportation, or any other thing to try and get your attention.
So in answer to your question, no you can not afk fish farm. We do not allow that on this server.
You can read the rest of the servers rules here :
https://snapcraft.net/rules/
Since your question is answered ill go ahead and lock this thread.