There is nothing as disappointing as investing a significant amount of time and money into a tank and then having the occupants not get along. That is why you should consider developing a community in your tank by only choosing species that will cohabitate in peace.
Some of the best species to keep together include Tetras, Cyprinids, Catfish, Mollies, and Angelfish. These varieties share similar temperaments and pH requirements. This means that they will be able to live together rather wellwithout becoming aggressive with one another. Although 
there are many other varieties that may do well together it could take a little bit of experimentation and research to find a combination that works for you.
To ensure that your tank remains happy and successful make sure that it will be able to house all of the animals after they have grown to their full sizes. Another important aspect of maintaining a community tank is the size of your shoals. Most of these species prefer to live in groups of no more than six of their own kind. With these simple steps, you will be able to keep a tank happy and healthy for as long as you possibly can.