Yes - in fact, selecting fish that swim at different levels is a good thing to do. Just as examples - look at danios (tend to swim towards the top), barbs and tetras (tend to swim in the middle) and corydoras (tend to shuffle around on the sand).
With a small tank. you need to be very careful what you choose. A rule of thumb is that you can have up to 1 inch of fish (at their full-grown size) per US gallon of tank capacity. 60 litres is about 15-16 US gallons. This rule, however, only applies to small fish - you can't put a 15" plec into your tank and hope he'll be OK!
You also need to think about the shape of your tank - many fish need swimming room and they tend to swim along the tank. So a long tank that is not very tall gives them more space than a tall tank that isn't very long! What are your tank dimensions?
You also need to look at the shape of the fish - for example, angelfish (no, I'm not advocating them for your tank) are tall with long fins, and they need a tall tank to stop them doing a Jaws impression with their fins stuck out of the water!
Choosing your fish is the interesting part!!!!