HI All. I'm new to this fascinating world of fish, and have been busy cycling a new tank for my 8-year-old son over the last month. Testing the water successfully last weekend, we were ready to add our first fish and went out and got 6 very small neon tetras. They seem to be doing fine (though one of them is smaller than the others and gets left out at feeding time...). We are hoping to add some more fish this weekend and would be grateful for any advice... What sort of fish would go well with the tetras, and would give plenty of variety and interest in the tank for an 8-year-old boy? (Obviously Dad is on perpetual standby...!) I was thinking of dwarf gourami and maybe guppy...maybe Cory? Would be great to have variety of size and speed, and occupying different levels of the aquarium. The tank is 70 litres, with silk plants. Any advice gratefully received.