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Tang
Yellow tang
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Family: Acanthuridae Genus: Zebrasoma
Species
Zebrasoma desjardinii Zebrasoma flavescens Zebrasoma gemmatum Zebrasoma rostratum Zebrasoma scopas Zebrasoma veliferum Zebrasoma xanthurum

Tangs are marine fish belonging to the genus Zebrasoma. The genus comprises seven species of pointed-snout, disc-like bodied, sail-like finned, single peduncular-spined fishes. Tangs are usually placid community fish, many forming large groups or shoals, although fiercely territorial against other tangs or similar shaped or coloured fish in an aquarium setting. All tangs are characterized by having a forward facing spine on each side of the caudal peduncle (visible as a short, horizontal stripe on the base of the tail in the above picture). This spine, apart from terminating in a point, has angular edges that result in a scalpel-like sharpness along its length also. When alarmed, tangs can erect the spines sideways and slash at their opponent with rapid sideways movements of the tail. In some surgeons, the spines are fixed in the offensive position. The family name reflects this nature, meaning, literally, "Thorn Tail".

Care must be exercised by aquarists should it be necessary to handle these fish. An encounter with even a small, frightened tang can result in a wound requiring stitches. Large specimens are quite capable of inflicting deep, life-threatening injuries - an adult Sohal Surgeon may have spines 4cm long, quite capable of reaching the femoral arteries of an unfortunate diver. There is some evidence to support the claim that in this fish in particular, the spines are either venom tipped or coated with epithelial cells (as in some urchins) which further complicate any injury. Colloquially described as a "Fish with a flick-knife", due mainly to their calm nature, such attacks on humans are rare. Aggression in tangs is usually confined to presenting their tails to a would be predator or attacker and is usually minimal against conspecifics, some however have noticed the purple tang, clown tang, spotted unicorn tang, and sohal tang to be more aggressive than most. Most aggression however is due to territory disputes.

Tangs are also very sensitive to disease in the home aquarium. It is usually necessary to quarantine the animals using copper sulfate or formalin for a period of around 2 weeks.

Adults range from 6 to 15 inches in length and most grow quickly even in aquariums. When considering a tang for an aquarium it is important to consider the size to which these fish can grow. Larger species such as the popular regal tang (of Finding Nemo fame), naso or lipstick tang, clown and sohal tangs can grow to 15 inches and require swimming room and hiding places.

Many also suggest adding aggressive tangs to the aquarium last as they are territorial and may fight and possibly kill other fish.

Tangs primarily graze on macroalgae, such as caulerpa and gracilias, although they have been observed in an aquarium setting to eat meat-based fish foods. A popular technique for aquarists, is to grow macroalgae in a sump or refugium. This technique not only is economically beneficial, but serves to promote enhanced water quality through nitrate absorption. The growth of the algae can then be controlled by feeding it to the tang.

The character "Dory" is a regal tang fish. This picture, taken in a zoo aquarium, shows the astonishing blue of the real fish.

Surgeon Fish are a group of saltwater fish from 6 related genera (Acanthurus, Ctenochaetus, Naso, Paracanthurus, Zebrasoma and Prionurus) which inhabit shallow reefs and beds of seagrass from the east coast of Africa northward to the Red Sea, and over the broad span of the Atlantic and Indo-Pacific oceans. The ideal temperature of their habitat is between the middle 70s and low 80s Fahrenheit (25 to 30 °C). The terms Tang & Surgeon are often - erroneously - used interchangeably when referring to certain members of the 6 genera, however only the Zebrasoma genus can be correctly termed "Tang". For example, Ctenochaetus Tominiensis is often attributed the common names "Tomini Tang" or "Goldrush Tang", when in actuality it belongs to an entirely different genus. As far as common names mean anything at all, a correct one would be "Tomini Surgeon".

The 2003 Pixar-animated movie Finding Nemo featured Dory, a regal tang, and "Bubbles", a yellow tang.

• Fishwatcher's Guide - Zebrasoma