The Red Sea sailfin tang or Desjardin's sailfin tang (Zebrasoma desjardinii) is a marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

 tang in the fish family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Acanthuridae

Acanthuridae

Acanthuridae is the family of surgeonfishes, tangs, and unicornfishes. The family includes about 80 species in six genera, all of which are marine fish living in tropical seas, usually around coral reefs...

. They originate in the lagoons and reefs of the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 from the southern Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

 to KwaZulu-Natal Province in South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 and as far east as India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 and Java. They may live at water depths of 2 - 30 m (6.5 - 100 ft) or more. The fish grow to a maximum length of 40 cm (16 in).

Red Sea sailfin tangs natively live in a tropical climate and prefer saltwater

Seawater

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 with a specific gravity

Specific gravity

Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 of 1.020 - 1.025, a pH

PH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 between 8.1 and 8.4 and an ideal temperature range of 22 - 26 C (72 - 78 F).

The fish are pair spawners

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

, a typical trait of other fish in the Zebrasoma

Zebrasoma

Zebrasoma is a genus of marine fish composed of seven species of pointed-snout, disc-like bodied, sail-like finned, single peduncular-spined fishes. Zebrasoma are usually placid community fish, many forming large groups or shoals, although fiercely territorial against other tangs or similar shaped...

genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. This differs from the group spawning typical of the Acanthuridae

Acanthuridae

Acanthuridae is the family of surgeonfishes, tangs, and unicornfishes. The family includes about 80 species in six genera, all of which are marine fish living in tropical seas, usually around coral reefs...

family. The juvenile fish live in the inner reef areas.

As a juvenile, the Red Sea Sailfin tang is almost indistinguishable from its Sailfin cousin, Zebrasoma veliferum

Zebrasoma veliferum

The sailfin tang is a marine reef tang in the fish family Acanthuridae. They may live at water depths of 1 - 60 m or more. The fish grow to a maximum length of 40 cm . Zebrasoma veliferum has an extensive range throughout Oceania, the Indian Ocean, and the South Pacific. Zebrasoma veliferum is a...

. But as the Red Sea sailfin tang ages, it begins to develop white spots on the head, orange spots on the sailfins, and vertical orange stripes on the body. In addition to this, its tail changes from being translucent to black and blue with white spots.