Louse Fish, Phtheirichthys lineatus (Menzies 1791)

Other Names: Lousefish, Slender Remora, Slender Suckerfish

A Louse Fish, Phtheirichthys lineatus. Source: Australian National Fish Collection, CSIRO. License: CC BY Attribution-Noncommercial

A rare slender bluish-black suckerfish, abruptly white below, with three stripes along the side - upper stripe pale blue, middle stripe black, lower stripe silvery. Sucking disc on head has 9-11 plates.

Video of a Louse Fish (aka Slender Suckerfish) at Cabilao, Philippines, November 2009.
Second video of a Louse Fish (aka Slender Suckerfish) at Cabilao, Philippines, November 2009.

Cite this page as:
Bray, D.J. 2017, Phtheirichthys lineatus in Fishes of Australia, accessed 20 Apr 2021,

Louse Fish, Phtheirichthys lineatus (Menzies 1791)

More Info


Great Barrier Reef, Queensland. Elsewhere the species is circumglobal in tropical and subtropical waters.
A rare oceanic suckerfish that attaches to large bony fishes (especially barracudas), sharks and sea turtles; also clings inside gill chambers.


Dorsal fin 32-38; Anal fin 31-38; Pectoral fin 17-21; Pelvic fin I, 5; Sucking disc 9-11 plates; Gill rakers 1-3 + 14-17; . 

Body very elongate (depth < 10% of SL); sucking disc small, reaches to above ~centre of pectoral fin; jaws broad, lower jaw projecting; pectoral fins pointed; dorsal and anal fins long-based; pectoral fins high on body; pelvic fins close-set, below pectoral-fin base; caudal fin with convex to W shaped margin (central rays filamentous in juveniles); scales small, smooth, embedded.


Bluish-black above, abruptly white below, silver below; a faint dark stripe, bordered above and below by thin pale stripes, along the mid-body; tail black with white upper and lower rear margins.

Species Citation

Echeneis lineata Menzies 1791, Trans. Linn. Soc. Lond. 1(21): 187, pl. 17(1). Type locality: tropical Pacific Ocean.


Bray, D.J. 2017


Australian Faunal Directory

Louse Fish, Phtheirichthys lineatus (Menzies 1791)


Collette, B.B. 1999. Family Echeneidae. pp. 2652-2654 in Carpenter, K.E. & Niem, T.H. (eds). The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 4 pp. 2069-2790. 

Collette, B., Smith-Vaniz, W.F., Williams, J.T., Pina Amargos, F. & Curtis, M. 2015. Phtheirichthys lineatus. (errata version published in 2017) The IUCN Red List of Threatened Species 2015: e.T190461A115323797. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T190461A16510667.en. Downloaded on 01 July 2017.

Gray, K.N., McDowell, J.R., Collette, B.B. & Graves, J.E. 2009. A molecular phylogeny of the remoras and their relatives. Bulletin of Marine Science 84(2): 183-198 

Menzies, A. 1791. Descriptions of three new animals found in the Pacific Ocean. Transactions of the Linnean Society of London 1(21): 187-188 pl. 17(1) 

O'Toole, B. 2002. Phylogeny of the species of the superfamily Echeneoidea (Perciformes: Carangoidei: Echeneidae, Rachycentridae, and Coryphaenidae), with an interpretation of echeneid hitchhiking behaviour. Canadian Journal of Zoology 80(4): 596-623.

Trnski, T.  2015. 176 Family Echeneidae (pp. 1236-1243), in Roberts, C.D., Stewart, A.L. & Struthers, C.D. (eds) The Fishes of New Zealand. Wellington : Te Papa Press Vol. 4 pp. 1153-1748. 

Whitley, G.P. 1949. Sucking fishes. Australian Museum Magazine 10(1): 17-23.

Quick Facts

CAAB Code:37336003

Conservation:IUCN Least Concern

Depth:1-50 m

Habitat:Oceanic, pelagic

Max Size:76 cm TL

Species Image Gallery

Species Maps

CAAB distribution map