Common name: Keeled boxfishes, temperate boxfishes, trunkfishes

A small family of oval to round fishes with bodies almost completely encased in a bony carapace formed from large thickened scale plates, usually hexagonal in shape and firmly sutured to one another; except the caudal peduncle which has isolated plates to allow tail movement. All species have very small mouths and often locate their invertebrate prey by blowing a jet of water onto the sediment. See Matsuura 2014.

Boxfishes lack fin spines and pelvic fins, and the short-based dorsal and anal fins are set far back on the body.

The rigid plates end before or on the tail base which is never completely enclosed in fused plates. The carapace has a series of longitudinal ridges, including a ventral ridge, and bear large fixed spines in some species.

Cite this page as:
Dianne J. Bray, Temperate boxfishes, ARACANIDAE in Fishes of Australia, accessed 20 Jul 2024,

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Family Taxonomy

A small family with 12 species in six genera, with 9 species found in Australia.

Family Distribution

Indo-West Pacific

Family Description

Body nearly completely enclosed in a carapace formed of enlarged, thickened scale plates, usually hexagonal in shape and firmly sutured to one another (less so on the cheek to allow for breathing movements); the carapace with openings for the mouth, eyes, gill slits, and fins, and for the flexible caudal peduncle.

Body oval in cross section; scales large, hexagonal, fused into a rigid bony carapace, covering body in front of dorsal and anal fins; centre of each individual plate with a low tubercle and radiating low ridges connecting adjoining plates; surface features indistinct in large individuals.

Gill openings relatively short, vertical to oblique slits in front of pectoral-fin bases; mouth small, terminal, with fleshy lips; teeth small, conical, close-set, single row in each jaw; spiny dorsal fin absent; most dorsal-, anal- and pectoral-fin rays branched; pelvic fins absent.

Species are sexually dimorphic, and males often become brightly coloured and develop a hump on the head or elongate spines in some species.

Family Feeding

Carnivores, usually feeding on invertebrates such as crustaceans. Temperate boxfishes have very small mouths and often blow a jet of water onto the sediment to expose their prey.

Family Reproduction

The sexes are separate and fertilization is external; eggs and larvae are pelagic.

Family Commercial

Although of no interest to fisheries, temperate boxfishes are often taken as bycatch in commercial trawls.

Family Conservation

No species are listed in Australia. Some species distributed elsewhere have been assessed as Least Concern by the IUCN.

Family Remarks

Although the flesh not poisonous, a mucous toxin, ostracitoxin, is present and some species can secrete the poison under stress. This toxin kills other fish and, eventually the boxfish themselves if exposed to it. 

The precise location of this toxin in all species is not fully understood, and boxfish should be considered potentially toxic to humans and their consumption as food should be avoided.


Dianne J. Bray


Allen, G.R. 2006. Ostraciidae (pp 1901-1909). In: Beesley, P.L. & Wells, A. (eds). Zoological Catalogue of Australia. Volume 35 Australia : ABRS & CSIRO Publishing Parts 1-3 2178 pp.

Hutchins, J.B. & Swainston, R. 1986. Sea Fishes of Southern Australia. Complete field guide for anglers and divers. Perth : Swainston Publishing 180 pp.

Kuiter, R.H. 1993. Coastal Fishes of South-eastern Australia. Bathurst : Crawford House Press 437 pp.

Kuiter, R.H. 1994. Family Aracanidae. pp. 892-902, figs 788-794 in Gomon, M.F., Glover, C.J.M. & Kuiter, R.H (eds). The Fishes of Australia's South Coast. Adelaide : State Printer 992 pp. 810 figs.

Last, P.R., Scott, E.O.G. & Talbot, F.H. 1983. Fishes of Tasmania. Hobart : Tasmanian Fisheries Development Authority 563 pp. figs.

Matsuura, K. 2001. Families Ostraciidae, Aracanidae, Triodontidae, Tetraodontidae (pp. 3948-39570. In: Carpenter, K.E. & Niem, T.H. (eds) 2001. The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 6 pp. 3381-4218.

Matsuura, K. 2008. Family Ostraciidae (pp. 842-948). In: Gomon. M.F., Bray, D.J. & Kuiter, R.H (eds). Fishes of Australia's Southern Coast. Sydney : Reed New Holland 928 pp.

Matsuura, K. 2014. Taxonomy and systematics of tetraodontiform fishes: a review focusing primarily on progress in the period 1980 to 2014. Review for IPFC9 Special Issue. Ichthyological Research 62(1): 72-113. Open access DOI:10.1007/s10228-014-0444-5

Matsuura, K. & Yamakawa, T. 1982. Rare boxfishes, Kentrocapros flavofasciatus and K. rosapinto, with notes on their relationships. Japanese Journal of Ichthyology 29(1): 31-42 figs 1-13.

May, J.L. & Maxwell, J.G.H. 1986. Field Guide to Trawl Fish from Temperate Waters of Australia. Hobart : CSIRO Division of Marine Research 492 pp.