Any suggestions to fill out my tank?

I have absolutely no experience with cichlids and tiger barbs, so I can't answer that. What I'd do so you can have more fish is get a smaller and peaceful type of fish. Try male guppies and male platties. They are very colorful and friendly. Instead of fish for algae eaters, try snails. They are really fun to look at, too. And when they are up and about, they can cover quite a lot of ground in just a minute. You could also get 5 neon (or any other tetras) tetras to school together. Then, you can get some guppies, gouramis, platties, or other fish. To add some exotic colors, get a black molly. It'd be really cool to look at so many colorful fish, and then end up on a big solid black fish.