What fish should I put in my tank?

I bought a fish tank yesterday as my old one was too small. The old one was 45 litres (about 10 gallons) and my new one is 120 litres (30 gallons) I only have 2 fish, and angelfish (about 2inches long) and a Bala shark (about 2.5inches long, maybe 3). I was told that the shark needs to be in a shoal of maybe 3 or 4 so I need to get that. I'm thinking of adding, another angelfish 2 x Bala shark 2 x algae eaters (small) 1 x discus (baby) Maybe a few barbs and see where that gets me Is this too much or what can I put in to keep them happy. Also if someone can suggest a theme for my tank that would be great.