Striated surgeonfish

Geographical Origin and Habitat: Ctenochaetus striatus is widely distributed throughout the tropical Indo-Pacific, from the eastern coasts of Africa and the Red Sea to the Hawaiian Islands, Tuamotu Archipelago, and southern Japan. It inhabits a wide variety of marine environments, including sheltered lagoons, inner reef flats, and exposed outer reef slopes at depths ranging from 1 to 30 meters. This species is closely associated with the substrate, where it actively grazes.

Taxonomy and Morphology: Belonging to the family Acanthuridae (surgeonfish), it is characterized by a sharp, retractable scalpel-like spine on each side of the caudal peduncle, used for defense. The genus Ctenochaetus is distinguished by having flexible, bristle-like teeth and a disc-like mouth adapted for scraping unicellular algae, organic detritus, and associated blue-green algae from rock surfaces. It reaches an adult length of 24 cm.

Social Behavior: It is a highly active fish that swims constantly near the rockwork. In the wild, it is often found in small groups or in mixed schools with other surgeonfish. In captivity, it displays strong intraspecific aggression; it should not be housed with other members of the same species or similar Ctenochaetus species unless in a very large tank. It is generally peaceful toward non-surgeonfish tankmates.

Coloration and Sexual Dimorphism: The ground color of the body ranges from olive-brown to dark orange-brown, covered with numerous, fine longitudinal orange and blue-grey stripes along its sides. The head is decorated with tiny, bright orange or yellow spots, which are particularly prominent around the eyes. The caudal fin is dark and may have subtle blue margins along the edges.

Aquarium Setup: Requires a spacious aquarium of at least 250 liters with a large quantity of mature live rock. The rockwork should provide ample surface area for natural grazing as well as caves for hiding. Water movement must be strong and highly oxygenated, utilizing powerheads and a high-performance protein skimmer. A clear open swimming area in the front is necessary.

Diet and Feeding: The diet is primarily detritivorous and herbivorous. In captivity, it must be fed high-quality commercial pellets or flakes enriched with spirulina, dried nori sheets attached to a clip, and frozen foods like brine shrimp and mysis. Frozen foods should be fed as a supplement, not a replacement for its vegetative requirements. Feed several times daily in small quantities.

Water Quality: Maintain clean and stable water parameters: temperature 23-28 °C, pH 8.1-8.4, specific gravity 1.020-1.025, and KH 8-12. This surgeonfish is sensitive to high levels of nitrates and organic waste. Excellent gas exchange, regular water changes, and using activated carbon help maintain water clarity and prevent skin issues.

Compatibility and Cohabitation: It is 100% reef safe, as it does not harm corals or clams and is highly beneficial for controlling nuisance algae in the aquarium. It coexists peacefully with most reef fish. Avoid housing it with other Ctenochaetus or highly territorial Acanthurus species in smaller tanks to prevent aggressive encounters using their caudal spines.

Aquarium Breeding: Breeding in home aquariums is extremely unlikely and undocumented. In nature, they engage in mass group spawning, releasing eggs and sperm simultaneously into the water column, often timed with lunar cycles. The fertilized eggs are planktonic, and the larvae undergo a transparent acanthuriform stage before settling on the reef.

Risks and Diseases: This species is highly susceptible to marine ich (Cryptocaryon irritans) and marine velvet under stress or temperature fluctuations. Proper quarantine is strongly recommended. Providing a vitamin-rich diet is essential to prevent head and lateral line erosion (HLLE). Use caution during netting to prevent its caudal spine from getting tangled or causing cuts.