''Kuhlia marginata'', the dark-margined flagtail, spotted flagtail, silver flagtail, orange-finned flagtail, northern jungle perch or mountain bass, is a species of

diadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, a

flagtail The flagtails (' or ' in the Hawaiian language) are a family (Kuhliidae) of perciform fish of the Indo-Pacific area. The family consists of several species in one genus, ''Kuhlia''. Most are euryhaline and often found in brackish water, but th ...

from the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Kuhliidae. It is found in eastern Asia and Oceania.

Description

''Kuhlia marginata'' has a moderately deep, compressed body with a moderately pointed head. The large, oblique mouth is protractile with a projecting lower jaw. The mouth extends to just in front of the pupil. It is silvery in colour and is normally marked with dark spots on the posterior, dorsal part of the body and these merge towards the head to form a horizontal dusky band or the dark pigment is concentrated on the edges of the scales. Most of the snout and the tip of the chin are blackish. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

is pale with a black rear edge which gets wider towards the tips of the lobes, and has a very wide pale submarginal area which frequently has a chevron-shaped blackish band or a row of dusky spots running parallel to the edge. The caudal peduncle is marked with small blackish spots. The margin of the soft-rayed portions of the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

and anal fins has a thin white margin and has a broad blackish submarginal zone which gets thinner towards the rear, this is wider on the dorsal fin. There is a distinct patch of red colour on the anal fin and the upper and lower lobes of the tail are pointed. The dorsal fin has 10 spines and 10-12 soft rays while the anal fin has 3 spines and 11-12 soft rays.

Distribution

''Kuhlia marginata'' is a widespread Indo-Pacific specs which occurs from Japan in the north to Australia in the south and east into the central Pacific as far as the

Caroline Islands The Caroline Islands (or the Carolines) are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically, they are divided between the Federated States of Micronesia (FSM) in the ce ...

. Its Australian distribution extends from Cape Tribulation to the Russell River in

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

Habitat and biology

''Kuhlia marginata'' spends most of its adult life in freshwater where there are flowing rivers and in pools below waterfalls as far as upstream. It is frequently recorded in estuarine environments but rarely in the sea.

Spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

takes place in the sea and it remains in the sea as a larva and juvenile before migrating up rivers to mature. It cannot get past waterfalls so tends to occur in the lower and mid-catchments of river systems where it prefers steep fast-flowing streams. The juveniles leave the sea for freshwater at around in standard length and the females mature at standard length and males at when they migrate back to the sea to spawn. Chemical analysis of sample

otolith An otolith ( grc-gre, ὠτο-, ' ear + , ', a stone), also called statoconium or otoconium or statolith, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The sa ...

s suggested that many males do not return to freshwater after breeding but females may return to the sea to spawn several times during their lives.

References

{{Taxonbar, from=Q305817 Kuhlia Taxonomy articles created by Polbot Fish described in 1829 Taxa named by Georges Cuvier