When looking to buy a fish, you're going to need a variety of things.

First, you'll need a tank. The tank should be big enough for the fish to swim around freely. You will also need to go buy a filter that fits with the tank. You might need to invest in a heater if you choose to buy a tropical fish.

You should also buy a few things for the tank for the fish to hide in. Fish do not like to be in the open at all times, so they should have a few places to hide when they are not feeling social.

You'll need to pencil in some time every other week to clean 20% of your fish's water. At least once a month, the tank needs to be completely cleaned. Of course, you'll need to take immediate action if the water appears dirty, clouded, or otherwise different.