Flagtail

The flagtails (āhole^[4] or āholehole^[5] in the Hawaiian language) are a family (Kuhliidae) of centrarchiform ray-finned fish of the Indo-Pacific area. The family consists of 13 species in one genus, Kuhlia. Most are euryhaline and often found in brackish water, but the genus also includes species restricted to marine or fresh water.

Flagtail
Hawaiian flagtail (K. sandvicensis)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Centrarchiformes
Family:	Kuhliidae D. S. Jordan & Evermann, 1896[1]
Genus:	Kuhlia T. N. Gill, 1861[2]
Type species
Perca ciliate G. Cuvier, 1828[2]
Synonyms[3]
Boulengerina Fowler, 1907 Herops De Vis, 1884 Moronopsis T. N. Gill, 1863 Paradules Bleeker, 1863 Platysome E. Liénard, 1832 Safole D. S. Jordan, 1912

Several species are known as Hawaiian flagtails, particularly K. sandvicensis and K. xenura.

Etymology

The genus Kuhlia is named for the German zoologist Heinrich Kuhl (1797–1821).^[6]

Description

The distinctive characteristic of these fish is a scaly sheath around the dorsal and anal fins. The dorsal fin is deeply notched between the 10 spines and the 9 to 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 (20 in) at most.

During the day, they usually school, dispersing at night to feed on free-swimming fish and crustaceans.

Ecology

A study of sperm motility in Kuhlia marginata found that sperm were most active in water with salinity between 25 and 35 parts per thousand, indicating that the species spawns in seawater rather than in rivers. This provided the first experimental evidence that K. marginata is catadromous, migrating from freshwater habitats to the sea to reproduce. Estimation of spawning sites in the spotted flagtail, Kuhlia marginata, based on sperm motility.

Analysis of otolith strontium-to-calcium (Sr/Ca) ratios confirmed that Kuhlia marginata spends its early life stages at sea before migrating to freshwater, then returns to the ocean to spawn. The study also found that males typically die at sea after spawning, while females may return to rivers and spawn multiple times during their lifetime

In Hawai‘i, flagtails (Kuhlia spp.), known locally as āholehole, inhabit a wide range of environments, including marine, estuarine, and freshwater habitats. These fishes play an important ecological and cultural role in Hawaiian coastal systems. Some use them as a food source and cultural ceremonies.

Species

The currently recognized species in this genus are:^[7]

• Kuhlia caudavittata (Lacépède, 1802)

  

  A school of young Kuhlia caudavittata.

• Kuhlia malo (Valenciennes, 1831)
• Kuhlia marginata (G. Cuvier, 1829) (spotted or dark-margined flagtail)
• Kuhlia mugil (J. R. Forster, 1801) (barred flagtail)
• Kuhlia munda (De Vis, 1884) (silver flagtail)
• Kuhlia nutabunda Kendall & Radcliffe, 1912 (Rapanui flagtail)
• Kuhlia petiti L. P. Schultz, 1943
• Kuhlia rupestris (Lacépède, 1802) (rock flagtail, jungle perch)
• Kuhlia salelea L. P. Schultz, 1943
• Kuhlia sandvicensis (Steindachner, 1876) (Hawaiian flagtail)^[8]
• Kuhlia sauvagii Regan, 1913
• Kuhlia splendens Regan, 1913
• Kuhlia xenura (D. S. Jordan & C. H. Gilbert, 1882)^[8]