Fowler's surgeonfish

This species is primarily native to the Western Indo-Pacific, with populations concentrated around the Philippines, Indonesia, Papua New Guinea, the Solomon Islands, and northern Australia. It inhabits outer reef slopes and steep drop-offs exposed to strong ocean currents, at depths ranging from 10 to 50 meters, preferring coral-rich zones.

Belonging to the family Acanthuridae, Acanthurus fowleri features an oval-shaped, laterally compressed body. Adults can grow to an impressive maximum size of approximately 45 centimeters in length. The mouth is positioned low on the head, which is ideal for grazing on algae. It possesses sharp, venomous spines on the sides of the caudal peduncle.

It is a solitary and highly territorial species that patrols large territories on the coral reef. In the aquarium, its behavior is aggressive and dominant, especially toward other surgeonfish of the same genus or species with similar patterns. It should be introduced last in large setups to minimize territorial aggression.

The adult coloration consists of an olive-brown body decorated with fine, wavy blue-gray lines. The defining feature is a black, horseshoe-shaped mark ringed in electric blue located immediately behind the eye. The caudal fin is dark with a distinct white margin. No visible external sexual dimorphism is present between males and females.

To accommodate a mature adult, a giant marine aquarium of at least 700 liters is required. The tank must feature exceptionally strong water movement, generated by high-powered wavemakers, and high oxygenation. The rockwork should contain established live rock for grazing but must leave most of the tank's volume open for swimming.

It is a primarily herbivorous fish. In captivity, it must be fed a constant diet of high-quality vegetable matter, including dried nori sheets, spirulina, and specialized veggie pellets. It also grazes on filamentous algae growing on the rocks. Supplement the diet with small portions of frozen mysis and brine shrimp to boost immunity.

Demands pristine water quality and extremely stable parameters. Keep temperature between 24°C and 26°C, pH from 8.1 to 8.4, specific gravity from 1.021 to 1.025, and KH stable between 8 and 12 dKH. Organic wastes like nitrates and phosphates must be kept low. A high-end protein skimmer and activated carbon filtration are required.

This species is reef safe and will not harm corals or ornamental invertebrates. However, due to its aggressive nature, it should not be housed with conspecifics or similarly looking tangs like Acanthurus bariene. It coexists well with other active and robust fish such as large wrasses, triggers, and large angelfish.

There are no recorded instances of this species breeding in home aquariums. In the wild, they are broadcast spawners that release pelagic eggs into the water column. The eggs drift with ocean currents and undergo a long, complex larval phase that requires specialized live feeds that cannot be cultivated in typical home systems.

Highly susceptible to marine ich (Cryptocaryon irritans) and marine velvet (Oodinium) due to its thin mucus layer. It is also prone to Head and Lateral Line Erosion (HLLE) if water conditions degrade or if its diet lacks necessary vitamins. A strict quarantine period and a UV sterilizer are strongly advised.