Most beginning aquarium owners are overwhelmed with the large number and variety of decisions required when setting up a new aquarium. The owner must decide on the type, size, and placement of the aquarium; whether it will be freshwater or saltwater; live or plastic plants; types of filters, heaters, lights, and food; and a hundred other technical questions that must be answered for designing a proper aquarium capable of maintaining its inhabitants.

Unfortunately, the last decision that is often made concerns the type and number of fish that are going to live in the aquarium. When the owner does decide to source fish it is often done based on color and appearance. As a result, many new aquariums fail to thrive, and many fish perish as a result.

The correct way to set up a new aquarium (after you are sure a fish aquarium is right for you) is to first research and decide what type of fish you would like to have in the aquarium. There are over 25,000 identified species of fish and over 3,000 of these are available to the aquarist. To help narrow down your list of desirable fish you need to consider all the following questions about the potential candidates:

• How big is the fish going to get?
• If the fish gets large, will it prey on or frighten smaller fish in the aquarium?
• Is the fish too small to fit in with the other fish in the aquarium?
• Is the fish territorial and will it require a large space of its own?
• Does the fish eat other fish (many tropical fish do)?
• Does it nip the fins of other fish?
• Is it aggressive - or is it too shy and nervous to live with certain other species?
• Does it eat live plants?
• Does it dig in the bottom of the aquarium?
• What kind of water does it require (pH, hardness, temperature, etc.)?
• Is it available where you live?
• What does it cost?
• Is it raised domestically or live caught?
• Does this particular fish need to live in groups, or does it prefer to live alone?

Once you have decided what fish you would like to have in your aquarium, then the rest of the decisions will fall into place much easier. One of the most important steps to take is to build the aquarium around the chosen fish species, not the other way around. You will be much more successful and have healthier fish if you build your aquarium around the needs of the fish rather than around your desire to have an attractive aquarium. If you create an aquarium where the needs of the individual fish in the aquarium are placed first it will be both healthy and beautiful.

The type, size, and location of the aquarium will be tailored to best suit the species of fish you choose. The filtering and heating choices will be based on the type of fish you choose. The plants, lighting, food source, and substrate choice will all be tailored to provide the healthiest and most natural environment for your fish species.

To repeat what we mentioned earlier, there are over 3000 species of fish available for the aquarium trade. To help make your search for the right fish easier, we have divided the most commonly available tropical fish into 7 main categories. Each one of these categories contains fish that are similar in many of their traits. However, it should be emphasized that this listing is just an outline and there are often many unique differences between fish in the same family and individual research into each specific species should be done before making your final decision.

Catfish: There are over 2,000 species of catfish each with their own unique characteristics but, as a group, none of these fish have scales. They are covered with skin or an armor-like plating. Many catfish are used as scavengers in aquariums and while many species are well adapted to this, some have very different eating habits. There is most likely a species of catfish that would work well in just about any type of aquarium setup. The key point is to find the catfish that will work best in your aquarium. Some things to consider when choosing a catfish are:

• Some catfish can get very large (over seven feet)
• Some catfish are nocturnal and need to be fed after dark
• Some catfish are specialized feeders and are not scavengers
• Coarse, sharp substrate (gravel) can damage or irritate some of the bottom feeding catfish
• Some catfish need to live in groups

Characiforms (characins, tetras, hatchetfish, pencilfish, splash tetras): This category includes a very large number of fish that are commonly found in Africa and the Americas. Some of the smaller species are extremely popular in community aquariums. Some of the larger ones (piranhas) are more difficult and better suited to experts. Many of these species are wild caught.

Cichlids: This category consists of a large very diverse number of fish that are commonly found in Africa, the tropical Americas, and Asia. The bright colors and diversity of habitat common to these species make them popular in many aquariums. The Cichlids all practice parental care which makes them more territorial. When they are guarding their young or eggs, they can be aggressive towards any other fish in the area and may even guard their nest areas when they aren't actively hatching young. This aggression makes most of them better suited to living in aquariums where other species of fish are not present. However, some species (dwarf cichlids and angelfish) will live together well in a community aquarium if the right conditions are provided.

Cypriniforms (barbs, danios, rasboras, sharks, loaches, goldfish, koi): These fish are found in many locations throughout the world and the species include both tropical varieties and cold water species such as the goldfish. Many of these species are popular in the aquarium because of their hardiness, ease of care, and willingness to breed. Many species are sociable and do well in a community aquarium.

Cyprinodonts (toothcarps,killifish): These fish are usually small and live and feed near the surface. The toothcarps consist of the egg layers that can be rare and difficult for beginners and the live bearers that are popular aquarium species such as guppies, mollies, swordtails, and platys.

Labyrinth Fish (gouramis, betta, paradise fish): This group of fish is very popular with aquarists. They are generally small, hardy, peaceful fish that are well suited to community aquariums except for some of the aggressive males of the paradise fish.

Rainbowfish (rainbowfish, silversides): The fish from this family come from a variety of different habitats and the individual needs of each species should be researched. These fish tend to have an iridescent quality to their skin that makes them change colors as they move through the light. Most species are small, peaceful, and colorful, and make good additions to a community aquarium.

Beginning aquarium owners will be faced with a variety of decisions and should start by researching the individual fish they want and their requirements. When they build their aquarium around the needs of the fish, they will be rewarded with a healthy, beautiful aquarium that will provide countless hours of enjoyment.

References
Bailey, M; Burgess, P. Tropical Fishlopedia. Howell Book. New York; 2000.
Burgess, P; Bailey, M; and Exell, A. A-Z of Tropical Fish. Howell. New York; 1998.
Burgess, WE; Axelrod, HR; Hunziker III, RE. Dr. Burgess’s Mini Atlas of Marine Aquarium Fishes. TFH. Neptune City, NJ; 1997.