Distribution

Tropical to temperate zones of the Indian Ocean and Western Pacific (including Melanesia, Micronesia and Polynesia), Red Sea.

Pterois volitans has been detected at the coast of Florida in 1985 for the first time. Together with P. miles this species has spread all over the Caribbean, the Mexican Gulf, Bermuda and the coastlines of the eastern USA.

  Fig. 4.28 Pterois volitans

Biology

In contrast to their close relatives the Scorpionfishes and Stonefishes (Scorpaenidae and Synanceyinae), Lionfishes are not reclusive. Relying on their conspicuous warning colouring in shades of brown or red with contrasting white stripes, they swim slowly and majestically through the reef, with fins spread wide. The long, thin fin rays surround the whole body like a shield, and their appearance alone gives the impression of impenetrability.

Fin rays are located on the dorsal fin (13), the pelvic fins (the front 2) and the anal fin (the front 3). These fin rays have grooves on both sides, are equipped with venom glands and are enveloped in a thin sheath of skin (Fig. 4.28).

Sometimes found in hollows or crevices, Lionfishes are also often known to swim close to places where there is a vertical drop in the substrate, such as coral reefs. They corner fish that swim by, and when the fish try to flee past their "puffed up" enemy, they often end up in the Lionfish's gullet.

P. volitans (Red lionfish), with a body length of up to 40 cm one of the largest species, displays a peculiar defensive behaviour towards potential enemies, in that it swims aggressively towards the enemy with the dorsal fin in front in order to stab the other fish. This type of active attacking behaviour might also exist in other Lionfishes.

P. volitans and  P. miles seem to be a serious problem in the new areas in the eastren Atlantic Ocean coast lines, where they have been introduced, maybe by private fish keepers. Since these "perfect invaders" are voracious predators and establishing very sucessfully, they pose a threat to the local ecosystem.

Risk

Lionfishes are popular aquarium fish and thus envenoming is not uncommon in aquarists, who can be stung through careless handling of the fish in the aquarium. Severe systemic envenoming is rare.

In a regional toxicology centre in the US state of Michigan, 23 patients were treated for Lionfish stings (Pterois sp.) during the period 1979–1988. All cases involved aquarists. All of the patients (over 90% male) were stung on the hand or a finger and presented with signs of envenoming. Pain and local swelling were the most common symptoms. Life-threatening systemic effects of the venom did not occur (Trestrail and Al-Mahasneh 1989). A similar series was documented in another toxicological centre in San Francisco. That centre treated 45 Lionfish stings (primarily Pterois volitans) during the period 1979–1983. Again every case but one involved aquarists. Pain and local swelling were the main symptoms. Systemic effects occurred in 6 patients (Kizer et al. 1985).

Literature (biological)

Halstead 1988, Russell 1965, Kizer et al. 1985, Williamson et al. 1996, Morris 2009

Catalogue of life

Comparative Toxicogenomic Database