I'm going to have to dissagree. Do not use aquarium salt, that is very stressful for freshwater fish.
The problem is Tiger Bards should not be kept with any fish that have long fins, period. They are a natorious fin nipper and are actually in general not good community fish at all.
Angelfish and Gourami should also not be kept together, Gourami can get quite aggressive when they get old, paticularly males which are the ones most people have (they are more colorful).
I know Petsmart labels Angelfish as 'semi-aggresive' but they really are not. They will go after and eat small torpedo like fish (think neon tetras) because that is their natural food, but they'll leave everything else alone provided they are not stressed. The only excpetion is during breeding and sometimes if you make new additions to the tank (new fish are usually juveniles which means small and thus food).
You can read up all kinds of information about Angelfish in the profile here, just click on the shaded name Scalare Angelfish
Unless you have a breeding pair (doubtful) they really should be kept in a larger group. The problem is, they will turn aggressive to new additions so with Angelfish it is best to get them all at the same time. In your case, I would stick with the two and let them live out their lives instead of attempting to get more.
But, you have to to either get rid of the Tiger Barbs (see if you can return them), or the Angelfish, they can not be kept together and all live. The Tiger Barbs will also probably go after the Gourami, they have the long feeler things that are just asking to be nipped.