how to know a betta will be suited to tm's?

[Friendlyfishies]

How can you tell if your betta will be suited to tankmates? Im thinking of putting a 20 gallon in the office where I work so I can watch my fishes...the 20 gal will become a home to Mr. Miyagi...
I plan to plant and cycle the tank
Then I would like to add a small group of maybe 4-5 friendly community fish or 4-5 cory cats (I havent decided which yet, trying to see what works best for my higher ph)
But im just not sure if it will stress him too much or if it will cause him to be aggressive, and I wont know til I do it, so then I may be strapped with 5 other fish et.
Any tips? Is there a way to know before hand how he will feel about other fishes?
Hes gentle with his snail, but hes a jumpy fish in general if that helps.
Thanks guys!

[LeoTheLakerBetta]

Usually at first they will be curious or defensive because they come into his territory. The best thing to do would be move his furniture around and then add the tank mates. Cories are good because they aren't top level swimmers so they won't get in your bettas way unless your betta decides to hang with them at the bottom.

[bluemoon11]

I would add your betta last as well. That way he won't claim his territory. Try putting your finger in the water, if you have a very aggressive betta he will attack it most likely, and likely any other fish put in the tank x