Amedion:
Not necessity to add salt in a Malawi-setup kinda tank you know? or any other fresh water tanks.
We add salt for 2 purposes(that i know of)
1) Helps the fishes to generate a layer of coating to protect itself against harmful parasites/illness bla bla bla
2) parasites that causes velvet and white spot/ich (i cant remmeber the name of it) hates salt!
For malawi tanks, things you'll need to dose are KH Buffers. You can DIY yours. Search online for the recipe. it's a mixture of baking soda, epsom salt...and somethign else i think. Not very sure. Helps maintain the pH above 7. Cos cichlids require pH that's above 7. Malawi's usually 7-8, Tanganyikans need 8 and above.
For your tank size, the only cichlid i can think of are Shell dwellers (Can be found at SLS...ONLY!) Or else, you can try South America cichlids like Apistogamma, Pelvicachromis etc. South America cichlids water parameter is the opposite of african cichlids. Do take note.
But they have very nice colorations and their size remain small (those i mention above), about 2 inches.
If you really want to have a salt water setup, be prepared to dish in more $$

It's more complicated than just adding SALT! Good luck!