Reef Stonefish

Introduction

The Reef Stonefish can be superbly camouflaged, often looking like an encrusted rock or lump of coral. The species is widely distributed throughout tropical, marine waters of the Indo-Pacific. It has stout dorsal fin spines which can inject an extremely poisonous venom.

Identification

Reef Stonefishes are extremely well camouflaged, looking like an encrusted rock or lump of coral. Individuals are usually brown or grey and may have patches of yellow, orange or red.

The Reef Stonefish has thirteen stout dorsal fin spines which can inject an extremely poisonous venom.

Two species of stonefishes are recorded from Australia, the Reef Stonefish and the Estuary Stonefish, Synanceia horrida. One of the ways to tell the two species apart is the placement of the eyes. The eyes of the Reef Stonefish are separated by a deep depression, however those of the Estuary Stonefish are elevated and separated by a bony ridge.

Habitat

They usually live on rubble or coral bottoms, often under rocks or ledges, but are also known to be able to bury in sand using their large pectoral fins.

Distribution

The Reef Stonefish is widely distributed throughout tropical, marine waters of the Indo-Pacific. In Australia it is recorded from much of the Great Barrier Reef, Queensland, to far northern New South Wales.

The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Source: Atlas of Living Australia.

Feeding and diet

The Reef Stonefish eats fishes and crustacea. It usually waits for prey to swim past, and then strikes with incredible speed. High speed camera equipment is required to record the feeding of this species.

Other behaviours and adaptations

The species is extremely well camouflaged and will not swim away when disturbed, but rather erects its poisonous dorsal fin spines.

Predators

Predators of the Reef Stonefish include sharks and rays. Jeff Johnson, Fish Collection Manager at the Queensland Museum stated:

"I have seen stonefishes in gut contents of large sharks (tigers and white sharks). Also small stonefishes are taken by Stokes Sea Snake, Astrotia stokesii. Stonefish bones have also been found in Aboriginal middens."

Danger to humans

The Reef Stonefish is the most venomous fish in the world. It has thirteen stout spines in the dorsal fin which can inject a highly toxic venom. The venom causes intense pain and is believed to have killed many Pacific and Indian Ocean islanders. No deaths have been recorded in Australia since European arrival (Underhill, 1987). An antivenom developed in 1959 further reduces the likelihood of death. Despite this, many people suffer the agony of a sting every year. Very hot water (not scalding) can be used to relieve the pain, but medical treatment should be sought.

The following information was kindly supplied by Andrew Wilner, MD, FACP, FAAN, neurologist, USA.

"Stonefishes are considered to be the most dangerous venomous fishes in the world (Ghadessy et al., 1996). Stonefish venoms have both cardiovascular and neuromuscular toxicity.

Stonefish venom is a mix of enzymes and non-enzymatic proteins (Ghadessy et al. 1996). The mechanism of action of stonefish venom is not completely understood. The Reef Stonefish and Estuarine Stonefish have different types of venom.

To respond to the question regarding neurologic toxicity, the venom of Synanceia horrida releases a neurotransmitter, acetylcholine, from the neuromuscular junction, which is similar to the mechanism of action of the excitatory neurotoxin from black widow spider venom (Lactrodecuts spp.) (Church and Hodgson 2002 – as S. trachynis).

However, there are other mechanisms of action as well, which include cytotoxic, myotoxic and other effects."

References

• Church, J.E. & W.C. Hodgson. 2002. The pharmacological activity of fish venoms. Toxicon. 40: 1083–1093.
• Eschmeyer, W.N. in Paxton, J.R. & W.N. Eschmeyer (Eds). 1994. Encyclopedia of Fishes. Sydney: New South Wales University Press; San Diego: Academic Press [1995]. Pp. 240.
• Ghadessy, F.J. et. al.1996. Stonustoxin Is a Novel Lethal Factor from Stonefish (Synanceja horrida) Venom. The Journal of Biological Chemistry. Vol. 271 (41): 25575–25581.
• Grobecker, D.B. 1983. The 'lie-in-wait' feeding mode of a cryptic teleost, Synanceia verrucosa. Environmental Biology of Fishes. 8(3/4): 191-202.
• Kuiter, R.H. 1996. Guide to Sea Fishes of Australia. New Holland. Pp. 433.
• Michael, S.W. 1998. Reef Fishes. Volume 1. A Guide to Their Identification, Behaviour, and Captive Care. Microcosm. Pp. 624.
• Paxton, J.R., D.F. Hoese, G.R. Allen & J.E. Hanley. 1989. Zoological Catalogue of Australia Vol.7 Pisces Petromyzontidae to Carangidae. Canberra: Australian Biological Resources Survey. Pp. i-xii, 1-665.
• Randall, J.E., Allen, G.R. & R.C. Steene. 1997. Fishes of the Great Barrier Reef and Coral Sea. Crawford House Press. Pp. 557.
• Underhill, D. 1987. Australia's Dangerous Creatures. Readers Digest. Pp. 368.