Convict Tang (Acanthurus triostegus)
Care Level: Moderate
Reef Compatible: Yes
Water Conditions: 72-78° F, dKH 8-12, pH 8.1-8.4, sg 1.020-1.025
Max. Size: 8″
Origin: Africa, Fiji, Indonesia, Solomon Islands, Sri Lanka, Tahiti
Minimum Tank Size: 125 gallons
The Convict Tang can be found in near-shore habitats and tide pools in geographical areas that range from the Arabian Peninsula, to the Hawaiian Islands, to Baja California extending down to Panama. It may be that wide range that make this fish very hardy in captivity, and easy to acclimate to a wide variety of tank systems. It is seen by many as an ideal fish to introduce a beginner to the hobby.
The fish obviously gets its name from its appearance that is colored bright white or silver highlighted by six vertical black bars extended the length of its body. This is considered to be “disruptive coloration” making it more difficult for a predator to get a sense of where the fish is. At night the colors become a very dark, near-black color, again to evade any night stalkers.
You will find their mouths are turned slightly downward that makes it easier to graze on algae, any activity you will find it doing quite often. Unlike most other surgeonfish the Convict females are larger than the males. Both sexes will typically reach 3.25-4.25 inches, but larger males usually top off just under 7 inches. Larger females, when fully grown, can actually reach a size exceeding 10 inches.
The sharp blades that you find on other surgeonfish are present on the Convict but are not well-defined.
Tank Conditions/ Acclimation
At least a 125 gallon tank is needed so that there is plenty of unobstructed swimming room. Do not keep in the tank with other Tangs as the larger fish will act aggressively toward the Convict including dominating the food supply and causing undue stress on the smaller Convict. You may add to the tank with other Convicts, but do so at the same time so that they may define their boundaries and acclimate together. If you are not able to introduce together, or you find the Tangs or other fish acting aggressive toward each other, you may consider rearranging the rock formations. This re-arranges the territories all together and can cut down on some of the possessiveness and bad behavior.
Surgeonfish caught in the wild and transported overseas can have any number of issues upon arrival in your tank. It is always best to quarantine, while you can observe and treat for any potential diseases. Convict Tangs happen to be particularly a risk for a number of ailments. They produce less body slime than other saltwater fish and this makes them more susceptible to diseases and parasites such as Marine Ich or White Spot Disease.
The Hawaiian name for the fish is manini, which literally translates to “no big thing”, but this Tang is anything but. What is lacks in size it more than make up for in utility. As a grazer the Convict will naturally keep the algae and seaweed levels in check. This serves two functions really, as it prevents any abundant growth from chocking off coral, and keeps your tank’s ecosystem in balance where harmful bacteria and parasites cannot multiple in the organic outgrowths.
If able, feed three times throughout the day rather than one large feeding. This allows for higher water quality and better long-term health for the fish. A healthy diet of pellets or died flake food, frozen meaty foods and algae or spirulina will keep your fish active and looking great.
Japanese Nori is a good idea to add to the tank, usually affixing it to the side with a vegetable clip is good. Frozen brine, mysis shrimp, mosquito larvae and grindal worms are a good idea for meaty supplements.
Consider soaking pellet food in garlic to fend off certain diseases like Marine Ich. There has also been a lot of reported success by hobbyist with boiled zucchini, broccoli and spinach.