A group of 5 or 6 Congo Tetra would be just fine in a 29 gallon tank.
Fundulopanchax and Aphyosemion are found in most of West African and you shold be able to rack down species (maybe not exact locations though) to match the fish you have. Personally I don't find that either genus makes a good dither fish though as they stay right at the water surface and like/need some plants at the top of the tank to hang out in. That said, if you are just looking to add more fish to the tank and possibly some color then you are on the right track.
The lamp eye killies (Procatopus and Aplocheilichthys) are more tetra like in that they are active schooling fish that are always swimming the open upper parts of the tank. They make a much more effective dither fish but their colors tend to be more reserved.