Convict Tang: Fish Species Profile

Characteristics, Origin, and Helpful Information for Hobbyists

black sturgeonfish

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Convict Tangs (Acanthurus triostegus) might not be the most colorful saltwater fish you can find, but with their flashy stripes and charming personality, these surgeonfish can be wonderful additions to the right saltwater tank. The black stripes on this tang harken to an old-fashioned prison jumpsuit, hence the name Convict Tang. In the wild, Convict Tangs live in large schools and spend their days foraging for food, namely seaweed/marine algae. Convict Tangs can be aggressive toward other tangs and fish of similar body types, but they are typically peaceful with other nonaggressive fish. 

Species Overview

Common Names: Convict Tang, Convict Surgeonfish

Scientific Name: Acanthurus triostegus

Adult Size: 8 inches

Life Expectancy: 5 to 7 years


Family Acanthuridae
Origin Indian Ocean, North, South and Eastern Pacific
Social Semi-aggressive
Tank Level All levels
Minimum Tank Size 100 gallons
Diet Omnivore
Breeding Group spawner
Care Intermediate
pH 8.1 to 8.4
Hardness 8 to 12 dGH
Temperature 72 to 78 F (22 to 25 C)

Origin and Distribution

The Convict Tang is a widespread species found in tropical waters throughout the world, including the Indo-Pacific, the Hawaiian Islands, the eastern Pacific (south from the Gulf of California through Mexico down to Panama, including the Revillagigedo Islands, Clipperton Island and the Galapagos Islands). They live in shallow reef areas where the feed mainly on marine algae growing on the reef. Convict Tangs are frequently collected for the aquarium trade in Hawaii and other parts of the South Pacific.

Colors and Markings

The Convict Tang has a white or silver body with six black vertical stripes. The top of the dorsal fin is painted with a pop of yellow. Convict Tangs can grow up to about 8 inches long, but many juvenile Convict Tangs available for purchase are smaller, ranging from less than an inch to about 6 inches long. 


Considered reef safe, Convict Tangs can be a good choice for a large saltwater aquarium, whether a community reef aquarium or a fish only tank. Convict Tangs can cohabitate peacefully with most other peaceful fish, but these fish may have issues with other surgeonfish, as well as with fish that have a similar body type like angelfish or butterflyfish. Some aquarists find that it is possible to house more than one tang together provided that the tank is large enough (at least 100 gallons), the tank is not overcrowded with too many fish and the fish are introduced to the thank in the correct order (when adding fish, always introduce the most aggressive species last). At the end of the day, though, the success of keeping more than one tang together in a saltwater aquarium depends on the individual fish involved. 

In the wild, Convict Tangs are schooling fish. It’s possible to keep several Convict Tangs together in a large and long tank, preferably a reef tank with lots of live rock and hiding places. If you want to try this, introduce all of the Convict Tangs at the same time for the best results. Note that success in keeping a group of Convict Tangs like this varies; some Convict Tangs will fight even in very large tanks. 

Convict Tangs do not tend to bother invertebrates like crabs and shrimp, and generally leave corals alone as long as they are getting enough to eat. They will graze on unsightly algae growing in the tank, making them excellent housekeepers.

Convict Tang Habitat and Care

Convict Tangs are swimmers. In their natural habit, Convict Tangs swim in schools, traversing the reefs all day as they graze on algae. In captivity, Convict Tangs need plenty of space for swimming. Although the number of gallons of the tank is important, equally important is the length of the tank. To allow enough space for swimming, Convict Tangs should be housed in tanks that are a minimum of 100 gallons (the bigger the better) and a minimum of 6 feet in length. Tanks this size and larger are ideal for all fish, but especially tangs because it avoids crowding and territorial spats with other fish, particularly other tangs. 

Convict Tang Diet and Feeding 

Tangs are somewhat delicate and prone to developing disease—keeping them well-nourished can help them fight off potential infections. Tangs are primarily herbivores, although many Convict Tangs also enjoy eating meaty foods like mysis shrimp and brine shrimp. In addition to meaty foods, feed lots of marine algae and seaweed based foods (frozen, flakes or pellets) to keep your Convict Tang plump and healthy. Many tangs love spirulina flakes and dried nori on a hanging veggie clip. Some aquarists like to soak nori and other marine-based foods in a vitamin supplement made specifically for marine fish to bolster health. If your tank contains live rock, the Convict Tang will graze on algae growing on the rocks. When well fed, Convict Tangs will generally leave coral alone, but hungry Convict Tangs have been known to pick at large polyp stony (LPS) corals. 

Gender Differences

Male and female Convict Tangs do not have discernable physical differences.

Breeding of the Convict Tang

Convict Tangs do not breed readily in captivity as their fry are free floating in the planktonic stage for several months and tend to be sucked up into aquarium filters. In their nature habitat, Convict Tangs are group spawners. At dusk, small groups of Convict Tangs will separate from the larger groups. The females will release eggs into the open water and the males will fertilize them. The Convict Tang larvae float along with plankton for approximately two months, after which time they make their way to sheltered places like tide pools where they are semi-protected as they continue to develop. Once large enough, juvenile Convict Tangs will venture out and join a school of other Convict Tangs.

More Pet Fish Breeds and Further Research 

If you like the Convict Tang, and you are interested in similar fish species for your saltwater aquarium, read up on:

Check out additional fish species profiles for more information on other saltwater fish.