Barbs do like space, but when in a school its a little like an elastic band, when the front part moves the #14### end is sure to follow, so you dont get them flying all over the tank like complete mentalists.
The school of 19 i have in my 90 litre are perfectly happy at the moment but they are still quite nippy to one another. If you done mind seeing the odd fin ripped here and there then its ok, but be prepared to live with a little damage. Imo, big tanks only, or species only tank for tigers.