I am a beginner with tropical fish , but i would like to know what fish would be good to put in. Ideally , i would like different types and sizes , that would be compatible and would be OK in a simillar PH and Temperature.
Thanks 
i recognise it… but what exactly is the nitrogen cycle? is it where you leave it to climatise for a week before you put the fishes in?
Have a read of this:
http://www.theaquariumwiki.com/Stocking_a_Peaceful_Community_Tank
Be cautious buying fish you like the look of in pet stores and don’t just mix and match random fish – it ends up looking a mess! A 70L isn’t a huge tank at all so don’t just go solely with any list people write on here, do your own research. Take a pen and paper to an aquatics store and write down species that take your fancy, come home and research them.
Remember you need to put your tank through the nitrogen cycle before you buy any fish.
Guppies, tetra, mollies, platies are all very good beginner fish.
Feed them Tropical fish flakes and these fish come in all different shapes and sizes.
Good Luck!!
Cool fish .
guppies, tetras, zebra danios, ghost shrimp. mollies, platties, fresh water snails, and algae eaters