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 24 May 2024, https://fishesofaustralia.net.au/home/species/4247

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

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CAAB distribution map