Choosing the right aquarium size is the first step in starting an aquarium. When it comes to choosing an aquarium, the rule of the thumb is: the bigger, the better. The larger the aquarium, the more volume of water it can keep, which in turn means more stable water chemistry. Choosing an aquarium should also be based on how much is comfortable spending and how much space you have for the aquarium.

Next, you need to choose the stand and location for your aquarium. A water-filled aquarium can be very heavy. Aquariums are also designed to spread out the weight evenly at the bottom. Make sure your aquarium stand is even and very sturdy. From here, the direction you will take will depend on whether you want a freshwater, saltwater, brackish, or planted aquarium.

Once you have determined your aquarium system, the next step to take is fill the tank with water, then set up the heater (with thermometer), lighting system, and filter. Don't add fish yet - the water in the tank has to be conditioned first using a process called biological filtration. The aim of biological filtration is to introduce beneficial bacteria into the tank that will help maintain the biological cycle in your aquarium. The bacteria will metabolize the waste products of fish and other aquarium inhabitants.

To cycle the aquarium water, you add a small number of disposable fish to the tank, letting them stay there until they have produced high concentration of ammonia (establishing biological filtration this way takes about 2 to 4 weeks). Another way to do this is to add ammonia to the tank. Let the water sit for about a month without adding any water at all. Once the biological filter is established, you are ready to add your pet fish to the aquarium.