About 2 inches top to middle that are easy to care for are things like platies. They come in a variety of different colors so you can choose the ones you prefer. Many would agree that for the lower part but active enough to be in other places are corydoras catfish. Both can be kept in most kinds of water that you will find. The thing is, there are lots of other fish that are colorful and relatively peaceful that you could get. It includes rasboras, several kinds of tetras, lots of other livebearers like guppies, swords, endlers and mollies. These are not 2 inch fish but are not enormous either . Guppies and endlers run a little smaller than your target size. Swords and mollies run a little larger. Many different sizes of tetras are found in the hobby. Rasboras are a schooling fish so they look pretty good swimming together but don't fill up space in a large tank because they are often all together. If you are just exploring the idea of keeping fish, go to a pet store and wander around looking at things you might like. Write down what interests you and remember that almost every fish you see will be quite young and smaller than full grown. When you have some ideas of what you might like, come back and ask lots of questions. Compatibilty, how many for a tank of a particular size, etc. Maybe we can help you get off on the right foot.