The flagtails are a 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...

 (Kuhliidae) of perciform fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 of the Indo-Pacific

Indo-Pacific

The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

 area. The family consists of several species in one genus, Kuhlia, of which, one, (K. rupestris), is freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

. The others are marine.

Description

The distinctive characteristic of these fish is a scaly sheath around the dorsal

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 and anal fins. The dorsal fin is deeply notched between the 10 spines and the 9-13 soft rays. The opercle has two spines, and the anal fin three. Their bodies are compressed and silvery, and they tend to be small, growing to 50 cm at most.

During the day they usually school, dispersing at night to feed on free-swimming crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s.

Species

• Kuhlia caudavittata (Lacépède, 1802).
• Kuhlia malo (Valenciennes
  Achille Valenciennes
  Achille Valenciennes was a French zoologist.Valenciennes was born in Paris, and studied under Georges Cuvier. Valenciennes' study of parasitic worms in humans made an important contribution to the study of parasitology...
  
  , 1831).
• Dark-margined flagtail, Kuhlia marginata (Cuvier
  Georges Cuvier
  Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
  
  , 1829).
• Barred flagtail, Kuhlia mugil
  Kuhlia mugil
  Kuhlia mugil, known also as Barred flagtail, Ocean Flagfish and Fivebar Flagtail is a species of fish in the Kuhliidae family that can live both in salt and fresh water. It is often associated with coral reefs....
  
  (Forster
  Johann Reinhold Forster
  Johann Reinhold Forster was a German Lutheran pastor and naturalist of partial Scottish descent who made contributions to the early ornithology of Europe and North America...
  
  , 1801).
• Silver flagtail, Kuhlia munda (De Vis, 1884).
• Kuhlia nutabunda Kendall & Radcliffe, 1912.
• Kuhlia petiti Schultz, 1943.
• Kuhlia rubens (Spinola
  Maximilian Spinola
  -Background:Spinola was born in Pézenas, Hérault, France. The family of Spinola was of very long standing and had great wealth and power in Genoa. Maximilian Spinola was a descendant of the famous Spanish General Ambrogio Spinola, marqués de los Balbases and much of his wealth derived from land...
  
  , 1807).
• Rock flagtail, Kuhlia rupestris (Lacépède, 1802).
• Kuhlia salelea Schultz, 1943.
• Hawaiian flagtail
  Hawaiian flagtail
  The Hawaiian flagtails are species of the genus of flagtail fishes found in the Hawaiian Islands.Two species are Kuhlia sandvicensis and Kuhlia xenura. K. xenura is endemic to the Hawaiian islands....
  
  , Kuhlia sandvicensis
  Kuhlia sandvicensis
  Kuhlia sandvicensis is a species of fish in the Kuhliidae family, found in both salt and fresh water.Endemic to Hawaii, the common name is āhole for the mature fish, andāholehole for the young...
  
  (Steindachner
  Franz Steindachner
  Franz Steindachner was an Austrian zoologist.- Work and career :Being interested in natural history, Steindachner took up the study of fossil fishes on the recommendation of his friend Eduard Suess...
  
  , 1876).
• also known as Hawaiian flagtail, Kuhlia xenura (Jordan & Gilbert, 1882).