Selection of Fish
The best thing to do when considering a home aquarium is to learn as much as possible about the various types of aquariums and species of fish. Your veterinarian, books, hobby magazines, the Internet, and your local pet store can all be good sources of information. A reputable pet store can be a great resource, because experienced employees are often knowledgeable not only about setting up and maintaining home aquariums, but also about local conditions (such as the characteristics of the tap water in the area) and in-store products. They can help you determine whether freshwater or salt-water is right for you. A saltwater reef tank with live corals requires much more maintenance and upkeep than a goldfish in a bowl. They can also help you sort through the wide variety of species and select fish that can be kept in the same type of environment and that are likely to get along with each other.
Once you are ready to begin selecting individual fish for your aquarium, you should look for healthy specimens. Healthy fish generally have smooth, unblemished scales, fins, and skin surfaces. Skin and fins should be intact, not bloody or ragged. Eyes should be bright, not cloudy. Fish should be swimming normally and steadily around the aquarium. Diseased fish often swim erratically (circling or drifting around the tank) or appear listless. The aquarium itself should be clean, and other fish in the environment should also appear healthy.
It is very important to make sure that your aquarium is properly set up and functioning for a while before you begin adding fish.