fish shell suggests commands in tmux I use fish shell, it's has option "suggests commands", so it is works like in the next screenshot. 

Examle:
You type command git status. In the next time when you type just g or git fish give you hint (like in the next screenshot), so you can press ctrl+F and you are getting full command git status(like tab arrow in other terminals).



But when I use tmux, this option doesn't work correct. There are no hint like in first screenshot. For examle: when I type git, it should be give me hint git status(like in first screenshot), but there are no any hint, I just see what I type. But when I press ctrl+F I get full command git status



In ubuntu it's works fine.
I actually encountered this problem recently on Ubuntu. It happens when tmux can't determine the number of colors supported by the terminal and sets it 8. If I run tmux -2, 256 colors are set and the command suggestions work as expected.

I found a detailed explanation here: https://unix.stackexchange.com/questions/118806/tmux-term-and-256-colours-support