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Interesting Facts about Brightly-Coloured, Invasive and Venomous Lionfish

Ornate Lionfish

'All that glitters is not gold' is a popular saying. It holds good for the Lionfish, a brightly-coloured fish which looks pleasant to the eyes. Its decorated external appearance is not at all a reliable indication of the true nature of this ornate fish.The fish is venomous and its beautiful tentacles may attract the prey. Its striking bright colours need to be seen as a warning sign about the danger ahead by other creatures in the sea.

This deceptive predator native to the Indo-Pacific, has now earned the reputation of the most aggressively invasive species and posed a major threat to the reef ecological systems in certain parts of the world.

Stay with me to know more about this brightly-coloured, invasive and venomous fish.

Brightly Coloured Lionfish

Elegant and Unique Lionfish

The lionfish has distinctive brown or maroon colour with white stripes or bands covering both head and body. It has unique tentacles above its eyes and below its mouth. There are 18 venomous spines which include 2 pelvic spines, 3 anal spines and 13 dorsal spines. All this makes lionfish an elegant creature.

The average size of a lionfish is almost 1 ft (.3 mts) though the largest of lionfish can grow up to 15 inches (0.4 mts) in length. It can weigh up to 2.6 pounds and average lifespan can extend up to 15 years. The Lionfish has been sighted down to the depth of about 1000 ft (305 mts).

Enjoy the Dancing Movements of the Lionfish

Commonly Studied Species

Recognised Species

Pterois is the genus for the common name Lionfish. This genus has 12 recognised species but three most commonly studied species in the genus are:

Pterois volitans: Also called red lionfish. This coral reef fish is native of the Indo-Pacific region, but has been found invasive in the Caribbean Sea and East Coast of the United States. About 93% of the invasive population is known to be red lionfish.

Pterois miles: This is the close relative of red lionfish having less angular head. It is also called common lionfish or devil firefish. There is variation in colour, from reddish to tan or grey. It has many thin, dark vertical bars on its head and body. It is mainly nocturnal and normally hides in the crevices during daytime. It feeds on small crustaceans and fish. It has now been reported in the eastern and central Mediterranean Sea, though it is also a native of the Indian Ocean.

Pterois radiata: This is a ray-finned fish and the only species among lionfish having spines without any markings. A pair of horizontal white stripes on its caudal peduncle makes it distinct and recognisable. This species is native to western Indo-Pacific region and is found on both inshore and offshore rocky reefs. This species is mainly nocturnal and feeds on invertebrates like shrimps and crabs.

Other Names

Pterois is the genus for the common name Lionfish

Pterois is also called: Zebrafish, Firefish, Turkeyfish and Butterfly-cod

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At Perth Aquarium

As Natives: Lionfish are natives to reefs and rocky crevices of the Indian and South Pacific Oceans (Indo-Pacific) and the Red Sea.

As Invaders: Lionfish have found their way to West Atlantic, Caribbean Sea as well as the Mediterranean Sea. Nearly 93% of the invasive population in the Western Atlantic is Pterois volitans. It is believed that accidental or even intentional disposal of lionfish from home aquariums has resulted in this invasion.

At Aquariums: Lionfish can make a uniquely beautiful addition to the home saltwater aquarium. It is successful only if there is an adequate space, reef and hiding space and proper food made available. Other smaller fish may not be able to survive in such aquarium.

Lionfish may find it difficult to survive water temperature below 50 degree Fahrenheit or 10 degree Celsius. Temperature can be the limiting factor for their presence in water in different parts of the world/home aquariums.

Left Middle: Egg sac of a female lionfish containing up to 20000 eggs. Bottom Right: Two egg balls floating alongside the lionfish

Left Middle: Egg sac of a female lionfish containing up to 20000 eggs. Bottom Right: Two egg balls floating alongside the lionfish

Female lionfish becomes sexually mature on attaining an age of one year, when it is 7 to 8 inches in length. Two gelatinous egg sacs, measuring 1 to 2 inches, are released frequently. In warmer climates each lionfish can release 10000 to 30000 unfertilised eggs at an interval of 4 days. Thus, about 2 million eggs can be released in a year by this prolific reproducer. In colder water this frequency is reduced to 3-4 months in a year.

Stung by Lionfish

The base of each of spines of lionfish has a reservoir of venom. Stinging is a mechanical process in which inward pulling off the spines puts pressure on the venom gland, which, in turn, triggers shooting up of the toxin to the tips of the hollow spines. But it is purely a defensive action which works as a deterrent to the predators. It is not used for hunting a prey.

Surprisingly, even a dead lionfish can cause stinging. Dead lionfish needs to be handled carefully to avoid mechanical process involved in stinging.

The venom of a lionfish is a combination of protein and Neuro-muscular toxin and neurotransmitter called oxyacetylene. A sting can cause extreme pain, sweating, nausea, vomiting and even breathing difficulties. On getting a sting, the first action should aim at decreasing pain and swelling. The National Oceanic and Atmospheric Administration recommends immersing the wound in hot water for about 30 minutes. The sting is rarely fatal. The flesh of lionfish is not poisonous.

Giant Grouper - A Predator

Venomous spines of lionfish are deterrents to the predators. But in the Indo-Pacific, their native habitat, the natural predators known for hunting lionfish are:

Large grouper, large eels, cornetfish, frog fish and even shark.

However, no known predators outside of its native habitat are known.

A Predator in Action

Inside Stomach of a Lionfish

Lionfish are known to be an extremely prolific invasive species. The invasion in the Atlantic is spreading at an extremely fast rate like plague. They are indiscriminate eaters and can consume a large number of organisms in one feeding. Their stomachs are known to have the capacity to expand up to 30 times their normal volume. Dissection of the stomachs of lionfish has shown not only large amount, but even different species of prey like small fish, invertebrates and molluscs. Their high reproduction rate, uncontrollable appetite and absence of known predators in the US Southeast and Caribbean coastal water are a great cause of concern to the scientists.

This invasion may result in ecological and economic harm to these areas. Apart from reducing the fish population in this area, they may harm reef ecosystems. Because of their indiscriminate eating nature, it is feared that they may also consume helpful species like algae-eating parrotfish. This, unfortunately, can pave the way for seaweeds to overtake the reef.

Imagine the Impact on Ecology

At present the approach is to reduce their numbers in the non-native, invaded regions through 'Lionfish Rodeos'. Scuba diving, free diving or snorkelling is used to remove as many lionfish as possible in specified areas by netting or spearing by these Rodeos.

Lionfish are known to be venomous but not poisonous. The National Oceanic and Administrative Administration (NOAA), an American Scientific Agency, is now involved in raising public awareness through 'Eat Lionfish' campaign to promote consumption of lionfish and make it a sustainable seafood choice.

These efforts are bound to have limited impact on containing the proliferation of lionfish.


Sukhdev Shukla (author) from Dehra Dun, India on June 05, 2017:

Thanks, Chitrangada. In spite of its being venomous many love to have it in their aquariums. Also, its invasion is a cause of worry, which needs to be tackled in coming days. I am glad you liked the Hub.

Chitrangada Sharan from New Delhi, India on June 05, 2017:

Very informative and interesting article about Lionfish ! I have seen this in pictures only . They look so beautiful. It would have been good had they not been venomous.

Enjoyed the videos, the pictures and the whole information!

Thanks for sharing!

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