The Achilles Tang, also known as the Red-tailed Surgeon, or Achilles Surgeonfish, is very dark brown to purple. It has bright highlights of white and orange around the dorsal, and anal fins. A white marking is also present on the gill covers and a striking orange teardrop is found near the caudal fin. The juveniles of this species have an orange marking by the tail in the shape of a streak instead of being teardrop in shape.
A 100-gallon aquarium or larger is necessary to provide plenty of swimming room. It is aggressive towards other Tangs and Surgeonfish, but peaceful with other fish
The Achilles tang is highly sensitive to damage from even minor ammonia levels and poor water quality. It is a fish that is difficult to capture without damaging them. The Achilles' skin is tender and easily scratched or marked. Its skin will show marks from any type of net, even a so called "soft" net
Maximum Size: This species grows to 8 inches in length.
General Size: This Achilles Tang is about five to eight inches in length.
Minimum Tank Size Suggested: A 100 gallon or larger aquarium provides a good environment for these Achilles Tang .
Tank Conditions: The Achilles Tang should ideally be kept in temperatures between 72 and 78 degrees Fahrenheit. A pH value of 8.1 or 8.4, and a specific gravity of 1.020 to 1.025 should be maintained. When kept with invertebrates, the specific gravity range should be 1.020 to 1.025, for the invertebrate species. In a fish only aquarium, the specific gravity should fall between 1.020 and 1.023.
Habitat: The Achilles Tang occurs in Hawaiian waters, but the distribution of this species extends from Hawaii southward to central Polynesia and westward through Micronesia and Melanesia, but it apparently does not extend to the Philippine Islands, the East Indies, and the Indian Ocean.
Feeding and Diet: The Achilles Tang fish is a herbivore. Its main diet consists of marine algae, having an unusually long digestive tract to digest the plant matter they eat. They are constant feeders and in nature spend most of their day grazing. A habitat with algae growth is good for them, which in turn helps to keep the algae in an aquarium cropped and in check.