You are suggesting 3 tetra species, which are all shoal fish (groups of at least 5 - 6). The normal 1 inch/ gallon rule translates for us metric system people to 0.75 cm/l. This you can double once the tank is mature and well-filtered.
For your tank, that would make around 41 cm of fish to start with. An example: the lemon fish get to measure around 4 cm. So one shoal of these would make 4 x 6 = 24 cm.
For this tank size I suggest you choose 1 tetra species as your shoalfish (don't choose the emperors as they require soft water), a clean up crew consisting of corydoras, maybe an otocinclus, and a centrepiece fish (maybe a dwarf gourami male; one of my favourites).
Both the odessa barbs and flying fox that you are suggesting need larger tanks than the one you currently have.
I have a 60 litre tank with: a shoal of serpae tetras, dwarf gourami, and peppered corydoras. Just to give you an idea.
I appreciate your help. You've given me a few ideas of fish to start off with.
Let me just mention that serpae tetras are notorious fin nippers, and that dwarf gouramis have long tempting appendages.... This is not to say disaster will happen in every single tank, but you are definitely taking a risk putting those two species together. Lemon tetras are also known fin nippers. It is often a good idea to make a first decision between active/boisterous tank or peaceful.
There is also a health risk in adding dwarf gouramis to any tank atm as a high proportion of them carry a virus that can also transfer to other fish. If you do decide to go with the gourami, I would choose a quieter tetra, like the black neon or the black phantom. Otherwise, Biulu's advice is very good- one school of tetras, a bottom crew and a centrepiece fish would make for a lovely tank.
As for the poster that said bleeding hearts don't get too big for a 2 foot tank- let me assure him that I have seen fully grown bleeding hearts and a full school of those would definitely not have enough swimming room in there.
