Many people think that having an aquarium and taking care of fish is a simple task. It is, really, unless people who are new to the hobby are misinformed by chain pet stores about taking care of fish.
Often times, chain pet store employees will recommend housing fish together that will not get along in a tank that is far too small with improper filtration. In addition to this, they will also not inform new hobbyists of cycling an aquarium with beneficial bacteria before ever adding fish to the tank.
This is what happened to me with my very first tank that I got my freshman year of high school. I did what the chain pet store employees told me to do, and in short time I was left with dozens of dead fish. I did not understand why this kept happening, so I decided to start researching. Fish need beneficial bacteria in the water column before they have been added to the tank. This means having a tank with live plants and perhaps something with a small bio load, like snails or shrimp. Only after the tank has stabilized should fish be added.
Fishkeeping does not have to be hard. It can be such an incredibly rewarding hobby if one is able to do proper research beforehand.