I recommend Rosy Barbs. Hardy, peaceful, energetic, colourful and their adult size is about 3" - perfect for this sort of tank. They like to be kept in groups of about 6 and will mix with most other fish.
I also recommend Angelfish. They are quite large so are a good centrepiece for a tank of this size and, once settled in, are very hardy. However they are not as easy to keep as a lot of other fish and I would recommend adding either one or a group (from the same tank in the store) once the tank has established its cycle.
Please stay away from fish labelled 'algae eaters'. They are messy, grow to a very large size and produce a huge amount of waste. They will uproot plants, dirty the tank very quickly and make your life hell. I learnt the hard way
Last edited by ollief9; 12-09-2012 at 05:24 AM.