With advances in equipment, saltwater aquarium enthusiasts are now able to keep a wider variety of fish than ever before. Here is a list of 20 of the most popular saltwater fish kept by hobbyists. Some are easy and recommended for beginners; others should be reserved for those with experience. The life expectancy listed is the common life span of these fish in captivity. With diligence and good care, life spans can be greatly prolonged and your fish may readily exceed these life expectancies. Surgeons. Surgeonfish get their name from the scalpel-sharp spines found at the base of the tail used for guarding territory and defense. Available in many different and spectacular colors and patterns, surgeons prefer vegetable foods and must have marine algae in their diets. Life span: 2 to 3 years.
Basselets. These colorful fish reach a length of about four to six inches and don hues of red, orange, yellow and purple. They are ideal for smaller reef tanks, although they do need space and need live food. Life span: 2 to 4 years.
Triggerfish. Triggerfish are so named because of their unusual ability to "lock" the dorsal fin into place so that it cannot be pulled from a hiding place. They have sharp outward pointing teeth that are designed for eating sea urchins and other invertebrates. They will accept most prepared and live foods. Life span: 2 to 4 years.
Boxfish/Trunkfish. Box and trunkfish are more challenging species for the saltwater aquarium and best left to experienced hobbyists. Boxfish are named for their square appearance. An important consideration is the toxin these fish release when they are aggravated or frightened. Feed small crustaceans and some greens. Life span: 2 to 4 years.
Angels. Highly prized by saltwater hobbyists, angels are among the most beautiful fish but are difficult to keep. These fish are sensitive to even small changes in water quality and can be tough to feed. Although they get along well enough with other species, they do not tolerate members of their own kind. Feed marine algae, fresh greens and frozen foods. Life span: up to 20 years.
Butterflyfish. Butterflies live well with each other but should not be kept with live coral, anemones or invertebrates as these animals are their natural food source. These fish need hiding places for the night. Feed as you would angels. Life span: 2 to 4 years.
Lionfish. Of all the saltwater fish available, the lionfish is always a showstopper. With its graceful long fins and striking coloration, the lionfish is a perfect blend of mesmerizing beauty and danger. Lionfish are aggressive carnivores and a diet of live food will be required to keep them happy. Their long spines are poisonous and can inflict painful injury. Life span: up to 10 years.
Mandarins. Most people stare in disbelief at the colors and patters of mandarin fish. Their pattern has been referred to as "psychedelic" because of the swirling royal blue, orange and purple markings. These fish are peaceful slow moving bottom dwellers that eat small crustaceans or bottom debris. Life span: 2 to 4 years.
Squirrelfish. Squirrelfish are one of the few red species. These fish require a large tank, they are active swimmers and energetic and will disturb more peaceful companions. They grow quite large in the tank, so its best to keep just one. They require a diet of live food, worms and small feeder fish. Life span: 2 to 4 years.
Clownfish. The sight of a clownfish protected by the graceful waving tentacles of a sea anemone is often what drives a hobbyist to begin a saltwater aquarium. They will do well in a tank without the company of an anemone. The presence of an anemone makes these fish territorial. Without an anemone, they get along quite well. Life span: up to 10 years.
Damselfish. Damsels are a good choice for beginning hobbyists. They adapt to aquarium feeding easily and usually have hearty appetites. Provide a large tank with a lot of coral formations if you plan on keeping several fish. Damsels will usually eat all prepared foods. Life span: 2 to 4 years.
Batfish. For a spectacular display of fins, the slow moving, peaceful batfish is a good choice. The large fins give the appearance of bat wings and can reach 15 to 18 inches in a spacious tank. They have been observed to "play dead" by floating on their sides when they feel threatened. Life span: 2 to 4 years.
Wrasses. Wrasses are most commonly kept as "cleaner fish." They will remove parasites from the skin of their tankmates. This can be bothersome in smaller, more delicate species. The majority of wrasses are bottom feeders. Life span: 2 to 4 years.
Blennies. These funny little fish have a big attitude for their small size. Blennies are in constant motion, won't back down from a fight and often start one. These fish are easy to feed. They don't mix well when kept in most community tanks but are fun to keep as a single species. Provide caves or individual habitats to prevent quarrels. Life span: 2 to 4 years.
Sea Horses. An aquarium dedicated to sea horses will be an endless source of fascination. These quiet, gentle creatures do best in a species tank. Sea horses need corals or marine algae on which they anchor their tails. They swim slowly and poorly and will not escape harassment or predation by larger fish. Keep water motion in the tank to a minimum. They eat brine shrimp and small live food. Life span: 3 to 4 years.
Filefish. Filefish have a long spine on their backs that can be "locked" into place. Filefish are generally peaceful but can be difficult to feed. Their natural diet consists of algae and marine polyps, which they pick up with their long snouts. It may be difficult getting them to accept prepared foods. The long-nosed filefish has an unbelievable color display of orange spots on a green body. Life span: 2 to 4 years.
Tobies. The only representative of this fish is the Moorish Idol. It is a shy browser and difficult to keep. This is one species best kept by advanced hobbyists. They are very sensitive to diet and water quality. They will squabble among themselves if more than one is kept in a tank. The long sloped dorsal fin and yellow/black/ white stripes distinguish it from its butterflyfish cousins. Life span: 2 to 4 years.
Eels. Keeping an eel may not appeal to everyone, but a few are interesting because of their markings. Eels are nocturnal and need good hiding places during the day. They will eat anything that passes by so don't keep them with small species or they are likely to be ambushed. Eels have been known to escape their tanks so a tight fitting lid is a must. Life span: up to 10 years.
Gobies. Gobies have developed a specialized pelvic fin that acts as a suction cup to help them cling to rocks. They are brilliantly colored, peaceful and easy to feed. Life span: 2 to 4 years.
Grouper. This is a large group of predatory fish that are kept successfully as juveniles. Mature fish will eat tankmates without hesitation. A diet of meat and live foods will be required. Many groupers are brightly colored and patterned. Life span: up to 10 years.
Other popular fish include goatfish, drums, cardinalfish, unicornfish, starfish, snapper, rabbitfish, puffers, parrotfish and hawkfish.