Scientific Name
Polydactylus microstomus

Common Name
Smallmouth threadfin

Biology
Dorsal spines (total): 9; Dorsal soft rays (total): 12-14; Anal spines: 3; Anal soft rays: 11 - 12; Vertebrae: 10 - 14. With 5 pectoral filaments; uppermost not reaching to (or extending slightly beyond) posterior tip of pectoral fin. Pectoral fin, rays short, 17-20% of SL; all rays branched except uppermost 1 or 2. Second dorsal spine long, 7-9% of SL. Well-developed swim bladder. A large black spot anteriorly on lateral line (Ref. 40958). Posterior margin of maxilla reaching to (or slightly short of) level of posterior margin of adipose eyelid. Lower tip of 7th proximal pterygiophore of 1st dorsal fin directed backwards. Lateral line squamation on caudal fin unbranched, extending to upper end of lower caudal fin lobe (Ref. 40970).

Classification

Classified By

Bleeker, 1851

Class

Ray-finned fishes (Actinopterygii)

Order

Perch-like fish (Perciformes)

Family

Threadfins (Polynemidae)

Distribution

Region

Eastern Indian Ocean and Western Pacific

Distribution

Eastern Indian Ocean and Western Pacific: Tamil Nudu, India to Myanmar and Phuket, Thailand; then from Taiwan to Indonesia and New Caledonia.

Range

26°N - 11°S, 77°E - 154°E

Environment

Climate

Tropical

Water Temperature From

Unknown °C

Water Temperature To

Unknown °C

Depth From - meters

2 m

Depth To - meters

55 m

Zone

demersal

Environment

Marine; brackish; demersal; depth range 2 - 55 m (Ref. 57343)

Trophic Level

3.9 s.e. 0.66 Based on diet studies.

Occurs in Marine / Salt water

True

Occurs in Brackish water

True

Occurs in Fresh Water

False

Occurs on Reefs

False

Is kept in Aquariums

False

Physical Size and Genetics

Maximum Length

25.0 cm

Common Length

20.0 cm

Phylogenetic Diversity Index

PD50 = 0.5000 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Human Uses and Population

Human Uses

Fisheries: of no interest

Vulnerability

Low vulnerability (17 of 100)

Resilience

High, minimum population doubling time less than 15 months (Preliminary K or Fecundity.)

Threat To Humans

Harmless

IUCN Red List Status

Least Concern (LC)