Long a favorite among aquarists, the angelfish is a tall fish that can be kept in a community setting, as long as its tankmates are not overly aggressive or habitual fin nippers. Fast-swimming fish may also make an angelfish nervous and may out-compete it for food.

The Arowana (Osteoglossum bicirrhosum) is a long and beautiful fish known for its voracious appetite and constant surface skimming, looking for things to fit into its mouth. It is native to waterways of the Amazon River and other areas in South America as well as Southeast Asia and Australia. It is a very popular fish for intermediate to expert aquarists as it swims fairly gracefully and with purpose and has a nice and powerful jaw.

Barbs are freshwater tropical fish within the genera Barbus and Puntius. They are very popular aquarium inhabitants, and the group includes well-known species such as the tiger barb and cherry barb. They do best in schools and keeping a few will decrease the chances that they will pick on other fish.

The betta, also known as the Siamese fighting fish, has become a popular fish among hobbyists primarily because of the male’s beautiful colors and lavish finnage.

The black molly (Poecilia sphenops) is a hybrid variation of the sailfin molly. It is a small fish, with males reaching about three inches in length and females slightly smaller.

The blue gourami is a robust fish that should be kept with other hardy, but mildly aggressive, community tank fishes. When kept with active, aggressive fishes it will often retreat to a corner and hide. House only one male per aquarium, as this species has a tendency to fight with one another.

Although the discus is a peaceful, schooling species, it is best kept in a species tank because its temperature needs are much higher than most other species can stand.

The goldfish is a form of wild carp that has been kept by humans as pets since at least 970 A.D., which is the first recorded instance of keeping and breeding them. The Chinese have developed different varieties of goldfish since then, as have the Japanese shortly thereafter.

Gouramis are freshwater fish in the family Osphronemidae. They are labyrinth fish, having the ability to breathe air through their labyrinth organ. Gouramis are typically found in Asia, India and South East Asia.

Although they are ideal community tank residents with fishes of similar size and temperament, if you intend to breed guppies, it is best to house them in a species-only tank. You can house three pairs in a 10-gallon tank or five to six pairs in a 20-gallon tank.

Jewelfish, also know as jewel cichlids, are members of the genus Hemichromis. They are native to West Africa, and are known to be aggressive in the aquarium. Generally, jewelfish do best in a monospecies setup, as other species will likely find them too difficult to live with.

The kissing gourami is a peaceful species that should be housed with fish of similar size and temperament. Males will occasionally fight by "pressing" their mouths together — hence the common name.

Koi are large domesticated carp commonly kept in backyard ponds. Some koi are exceptional specimens, called "show koi" and can be very expensive. Many pondkeepers keep less expensive pet koi; they may not have perfect colors and markings, but they are great pets.