Sohal surgeonfish

Geographical Origin and Habitat: Acanthurus sohal is endemic to the tropical waters of the Red Sea and the Persian Gulf. It primarily inhabits outward-facing coral reefs and shallow reef flats exposed to surge and wave action, at depths ranging from 1 to 10 meters. The species is highly adapted to high-energy zones with turbulent, oxygen-rich water where it swims continuously, defending territories rich in filamentous algae that grow on sunlit rocks.

Taxonomy and Morphology: Belonging to the family Acanthuridae and the genus Acanthurus. It exhibits an oval-shaped, laterally compressed body typical of surgeonfishes. Its mouth is small, equipped with specialized teeth adapted for grazing and scraping algae from rocks. It possesses sharp, scalpel-like retractable spines (caudal spines) on each side of the caudal peduncle, used for defense. Adults can reach a total length of 40 centimeters.

Social Behavior: Renowned as one of the most territorial and aggressive marine fish in the aquarium hobby. It displays extreme intolerance toward conspecifics and other surgeonfishes, particularly those with similar shapes or color patterns. It actively defends its territory by swimming rapidly around intruders and flashing or slashing with its sharp caudal spines. It should be introduced last.

Coloration and Sexual Dimorphism: The coloration is exceptionally striking: a light grey body marked with fine, horizontal black and electric-blue zebra stripes. The dorsal, anal, and caudal fins are black, highlighted with brilliant neon-blue borders. A vivid orange patch is located on the flanks just behind the pectoral fins, and the caudal spines are also orange. There is no visible sexual dimorphism.

Aquarium Setup: Requires an exceptionally large marine aquarium, with a minimum capacity of 700-800 liters (approx. 180-200 gallons) and a tank length of at least 200 cm to allow for open swimming. High-output wavemakers are necessary to recreate the strong, turbulent currents of its natural reef habitat. Live rock should be arranged to form caves and arches while leaving the center open.

Diet and Feeding: A strict herbivore requiring a constant supply of marine vegetation. The diet must consist primarily of dried seaweed (nori), spirulina, high-quality herbivore pellets, and vitamin supplements. Meaty frozen foods such as mysis, brine shrimp, and krill can be offered occasionally, but should not exceed 20% of the overall diet to prevent digestive disorders.

Water Quality: Demands clean, highly oxygenated water with stable parameters. Keep temperature between 24°C and 28°C (75-82°F), pH at 8.1 to 8.4, specific gravity at 1.022 to 1.025, and KH at 8-12 dKH. An efficient protein skimmer, strong mechanical filtration, and regular water changes are essential to keep nitrate and phosphate levels near zero.

Compatibility and Cohabitation: Due to its high aggressiveness, cohabitation is challenging. It must be kept as the only surgeonfish in the aquarium. Compatible tankmates include large, active, and robust species such as triggerfish, large wrasses, groupers, and large angelfish. Avoid housing it with slow-moving, shy, or small fish, which will be severely harassed.

Aquarium Breeding: Spawning in home aquariums is extremely difficult and undocumented due to the fish's pelagic spawning nature and the space required for courtship. In the wild, they form massive spawning aggregations, releasing eggs and sperm simultaneously into the water column during high tide cycles to ensure egg dispersal.

Risks and Diseases: Highly susceptible to external parasites like Marine Ich (Cryptocaryon irritans) and Velvet (Oodinium), especially when stressed during acclimation. It is also prone to Head and Lateral Line Erosion (HLLE) if its diet is nutritionally deficient or if water quality is poor. A strict quarantine protocol is strongly advised.