Before setting up an aquarium, you should research what kind of fish you like and find out how much space they need and what other breeds of fish they get along with....Do not trust the signs and people at the fish store--most of the time they are not accurate. There is endless information on the internet about fish, along with fantastic books on setting up a tank and making the perfect environment for the kind of fish you have. Some fish are shy and will hide a lot. Others are very outgoing and will be a the front of the tank all the time. The lifespans and size of the fish at full grown are very important as well. You will have great luck with keeping an aquarium if you are careful about how it is set up and think about the fish first. Having an aquarium is a lot of fun, and a lot of work. It is a great hobby to have....but too many times people don't know what they are getting into and the fish become a hassle and are considered disposable.