Kole tang

Geographical Origin and Habitat: Ctenochaetus strigosus is a species of surgeonfish endemic to the Hawaiian Islands, although related populations have been reported in other areas of the Central Pacific. It primarily inhabits shallow coral reefs and steep slopes exposed to marine currents, at depths ranging from 1 to 110 meters, preferring areas rich in hard substrate covered by a dense film of benthic algae and organic detritus.

Taxonomy and Morphology: It belongs to the family Acanthuridae. It shares the presence of sharp erectile spines on both sides of the caudal peduncle, used as defensive weapons. It features a specialized mouth with flexible, comb-like teeth, ideal for scraping the algal microfilm without damaging the rock or coral structure. It can reach a maximum length of about 16-18 centimeters in adults.

Social Behavior: It is an active and tireless diurnal swimmer. While peaceful towards most community fish, it exhibits strong intraspecific territoriality and can become highly aggressive towards other surgeonfish, particularly those belonging to the same genus Ctenochaetus or presenting similar body shapes and feeding habits.

Coloration and Sexual Dimorphism: The coloration of adults is extremely elegant: the body presents a purplish-brown or dark brown hue, crossed by thin horizontal blue or pinkish lines. The most prominent feature is a bright yellow ring surrounding the eye. The head is dotted with small bluish ocelli. There is no marked visual sexual dimorphism between males and females.

Aquarium Setup: Requires a spacious aquarium of at least 250-300 liters to ensure adequate linear swimming space. The setup must include a large amount of live rock arranged to create caves and open passages, while leaving ample room in the front. The rocks must be well-lit to promote the growth of natural microalgae which the fish grazes on constantly.

Diet and Feeding: It is a specialized detritus and microalgae grazer. Its diet in the aquarium must include large quantities of vegetable matter, such as dried nori seaweed provided via clips, high-quality spirulina-based pellets or flakes, and frozen vegetable preparations. It also accepts protein foods like mysis and brine shrimp, but these should only constitute a minor part of its overall diet.

Water Quality: Requires excellent water quality, with very high dissolved oxygen levels. Parameters to maintain are: temperature between 23 and 26 °C, pH between 8.1 and 8.4, specific gravity stable at 1.020-1.025, and KH between 8 and 12. Strong water movement via wavemakers and an efficient protein skimmer are necessary to replicate the conditions of Hawaii's exposed reefs.

Compatibility and Cohabitation: It is an exceptional fish for reef aquariums (reef safe), as it does not touch corals or invertebrates in any way. It can coexist peacefully with calm community fish such as clownfish, gobies, wrasses, and dwarf angelfish. Avoid housing it with other surgeonfish in the same tank unless the space is exceptionally large (over 500 liters).

Aquarium Breeding: Breeding in the aquarium has not been successfully achieved in captivity to date. They are pelagic spawners that gather in large groups in the wild, releasing eggs and sperm into the water column at dusk. The larval development goes through a prolonged planktonic stage (called acronurus) extremely difficult to manage and feed in controlled environments.

Risks and Diseases: It is particularly susceptible to parasitic skin infections such as Marine Ich (white spot) and Marine Velvet, especially during the introduction phase due to shipping stress. It requires high-quality nutrition to prevent the onset of Head and Lateral Line Erosion (HLLE). The use of a UV sterilizer is recommended to keep the pathogen load low in the tank.