My 5-gallon tank, which I have been working on for the last couple months when I can afford new things for it. Originally was meant as a breeding tank, but the fish were not cooperating, so I decided to set it up as a regular tank.
Left side: Rainbow (fancy tricolor crowntail/double tail mix)
Right side: female bettas Ruby (red female at top) and Echo (at the bottom)
The right side was originally home to Comet, but Comet is a very lazy betta who spends most of his time lounging around on the tank bottom. Ruby needed room to swim and Echo needed a place to heal, so I moved Comet out and put the girls in.
Ruby is recovering well from a battle with dropsy. Echo spent most of her time hiding in the big tank and her fins were getting chewed up by the other females. Both are very active. There were some interesting freakouts on their part for the first day or so, whenever Rainbow started flaring at them, but then they figured out The Pink Nutball is behind a wall and can't do anything but flare. So now they just ignore him.