Ya, i agree with everyone above. You have way to much open space. Get a few terra cotta pots, they are cheap and easy! Also i would suggest a filter.... and cycling before introducing the fish. Haste Makes WASTE! :D
Here is a pic of my sorority as of a few weeks ago, now i have a few shrimp, and oto (one died last night, found the shrimp chowing on him) a molly, and 6 girl. I have 4 live plants, 2 fake, (several betta bulbs still growing too) 3 cave/hiding hole, and a moss ball (which they all love lay on and kinda under lol). There is less free space so they dont see each other nearly as much if they look from one side of the tank to the other.
Hope this helps, and gives you more ideas :D
Sorry had to add this when i saw it: