Originally Posted by heythatsme
I wouldn't worry too much about them being sisters as long as the tank is heavily planted. They will stress out at first but as long as they CAN hide from one another, they usually won't bother. I now have 13 girls in a 29 gallon and they basically act like schooling fish. My recommendation is lots of floating plants that have roots that extend down, so the girls can hide from each other near the surface and get air or like OFL lots of tall plants. Caves are a little useless as long-term hiding places for a betta because they have to come up for air, so if they're being harassed a cave isn't a good place to hide, but floating plants are.
And the other girls know where the cave is. You'll quickly see them canvas the hideys. Something I often do for aeration is get a couple UGF pipe heads and stick them on both ends with an airstone in the bottom of about 8 inches of pipe... then whap it in a after-market heater clamp and stick it on the side. Goat absolutely adores this; gentle vibration, glass camping, all the tank smells and its a dead spot in the flow to sit on the suction cup/clamp. If the girls fight over camping spots, try getting some of the suction cups and just stick them in the tank so the C looks like that c. If the flow's low enough you'll find them resting there all the time.
The other thing I've noticed they like is ballooning: Going up under the bubbles at the end of my 4-way or staying in the center of the tom's feeder rings where all they have to remember to do is float. You can do this with "tied off" floating fern stuff as well. I even had one girl that liked to get up into the output baffle area of my 350b when the water level was low enough to slow the pump. She'd sit up there and wiggle off when she needed air. That's why I don't use the 350b any more.
I had to put it back in six months later and it wasn't maybe a minute before Emmy was climbing right back up in that slot.
Keep in mind that YOU are the girls' primary entertainment so anything that lets them lounge around while watching you is great... I've seen sections of three inch pvc with a chunk cut out so they hang into the tank, will make a couple. (fresh pvc needs water soaked in salted tap water for two days, vinyl chloride hurts the labyrinth)