Like TOS said, they look like they lose more because the water volume is smaller, but its not really more.
Microrasboras would be great fish for a 2.5g. They are tiny! You can see pictures and even order them from
http://www.franksaquarium.com.
You asked for pictures, so here's my 3g:
I have a 27w desk lamp over it for light. Only a Crowntail Betta in it...and some pond snails.
My filter came with the tank...its just a small one like the Azoo Palm filter or Red Sea Nano....its just right for the betta.