The best way to do it is to plan some cichlids or larger fish and then figure out what can stay, what has to go, and what you need to add. Cichlids comprise such a vast group of fish they can never, ever, be generalized. Your tank would be nice for something like a pair of Severums, and then you can choose some hardy fish to go with them. This type of cichlid is only mildly aggressive and because they have small mouths they're very limited to what can fit into them. Again I stress learning about them first so you have an idea of how they should be kept - cichlids are different then community fish, and randomly stocking different ones is playing with fire. If you do it right though, you can go with your idea and make it a great tank. Barbs are usually not so good with cichlids, while rainbows typically do well with them.