Convict Tang

Geographic Origin and Biotope: Ubiquitously distributed on a global scale, along the entire tropical belt of the Indo-Pacific Ocean and in the Eastern Pacific Ocean (up to the Gulf of California). Prefers quiet lagoon bays and estuaries teeming with immense shallow algal expanses.

Taxonomy and Morphology: Known as the Convict Tang, because of its livery that evokes the uniform of prisoners. Body decidedly shorter and more rounded than the Sohal. Despite its modest size, it is equally armed with retractable caudal spurs. Reaches about 27 cm (11 inches) in nature, but in aquariums it stays around 20 cm (8 inches).

Social Behavior: Peaceful and extraordinarily gregarious (atypical for the majority of Acanthuridae). Joins inextricably in immense schools that, like clouds of underwater locusts, overwhelm the territories of damselfish to depopulate the reef of benthic algae. Excellent character, shy if isolated.

Coloration and Sexual Dimorphism: Sober and elegant. The background of the body is a light ivory-cream (or opalescent pale green), crossed vertically by six clear and perfect black bands that descend from the back to the belly. Sexually monomorphic and devoid of the bright colors classic of the genus.

Aquarium Setup: Requires aquariums starting from 400 liters (100 gallons). Ideal to set up with live rocks positioned to form deep canyons; loving to travel in schools, in very large tanks it is highly recommended to insert at least 3-5 specimens (never 2, to avoid concentrated hierarchies). Loves strong currents but tolerates calm.

Diet and Feeding: The perfect lawnmower of the sea. Totally and hopelessly phytophagous. Its flattened mouth makes it suitable for scraping every blade of algae from the rocky surface. Continuously supply sea lettuce, dried red algae, spirulina flakes and frozen vegetable preparations.

Water Quality: Robust and less susceptible to variations than the Leucosternon. Prefers SG between 1.020 and 1.025 (often pushing almost into brackish waters in natural estuaries). Requires optimal oxygenation (pH 8.1-8.4) and a strong bacterial maturation in the tank with rocks widely covered with algal microfilm.

Compatibility and Tankmates: Probably the most peaceful surgeonfish existing (together with Ctenochaetus). Will ignore any other tenant and leave LPS, SPS, Zoanthids and Tridacna clams in total peace. If kept alone, it can become the object of fierce bullying by territorial Zebrasoma (Flavescens, Veliferum).

Aquarium Reproduction: Although in nature they show impressive and crowded pelagic reproduction rituals (cyclic "spawning aggregations" linked to the lunar phases), the spawning and artificial rearing of the very delicate larval stages in the home aquarium remain utopian.

Risks and Diseases: In tanks that are too clean (without algal films to graze) and in the absence of constant supplies of vegetable food, it is subject to very rapid undernourishment and death by starvation. It regularly suffers, like its cousins, from Cryptocaryon irritans infestations.