Lionfish: Characteristics, Behavior and Mating

Home | Category: Reef Fish


red lionfish (Pterois volitans) in Manado, Indonesia

Lionfish are venomous fish that get their name from their feather-like dorsal fins. They have also been called zebrafish because of their brown and white striped bodies and turkeyfish because of the flappy skin under their chin. There are different species of lionfish such as the zebra lionfish and the twinspot lionfish which display species-specific pectoral fins when threatened or trying to attract females .[Source: David Doubilet, National Geographic, November 1987 ┭]

Lionfish are carnivores that feed on small crustaceans and fish, including the young of important commercial fish species such as snapper and grouper. They are native to the Pacific Ocean and Indian Ocean, but are now established along the southeast coast of the U.S., the Caribbean, and in parts of the Gulf of Mexico. Since lionfish are not native to Atlantic waters, they have very few predators.

Lionfish belong the genus Pterois and characterized by conspicuous warning coloration with red or black bands, and ostentatious dorsal fins tipped with venomous spines. They can are generally found around the seaward edge of shallow coral reefs, lagoons, rocky substrates, and on mesophotic reefs at depths down to and past 100 meters (330 feet), They and can live in areas of varying salinity, temperature, and depth and frequently found in turbid inshore areas and harbors, They have also been called a devil fish, firefish, red lionfish, scorpion-cod, zebrafish, ornate butterfly-cod, featherfins, butterfly cod, Indian lionfish, soldier lionfish, and poison scorpion. Pterois species are popular aquarium fish. [Source: NOAA, Wikipedia]

Websites and Resources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Fishbase ; Encyclopedia of Life ; Smithsonian Oceans Portal ; Woods Hole Oceanographic Institute ; Cousteau Society ; Monterey Bay Aquarium ; MarineBio

Lionfish Venom

antennata lionfish

Lionfish have 18 venomous spines and are protected on all sides. Venom is stored in their dorsal, anal and pelvic spines. Although the lionfish stings are rarely lethal to humans, the venom can cause nausea, paralysis, convulsions, pain, vomiting, fever, headache, numbness, paresthesia, diarrhea, sweating, temporary paralysis of the limbs, respiratory suppression, heart failure, and even death. The pain of a lionfish sting delivered to a human can last for days and cause extreme discomfort.

The painful sting that can cause “changes in heart rate, abdominal pain, sweating, and fainting,” according to the Symptoms can last up to 30 days. Pterois venom produced negative inotropic and chronotropic effects when tested in both frog and clam hearts and has a depressive effect on rabbit blood pressure. These results are thought to be due to nitric oxide release. Fatalities are more common in very young children, the elderly, or those who are allergic to the venom. The venom is rarely fatal to healthy adults, but some species have enough venom to produce suffering for a period of several days. Moreover, Pterois venom poses a danger to allergic victims as they may experience anaphylaxis, a serious and often life-threatening condition that requires immediate emergency medical treatment. Severe allergic reactions to Pterois venom include chest pain, severe breathing difficulties, a drop in blood pressure, swelling of the tongue, sweating, or slurred speech. Such reactions can be fatal if not treated. . Experimental evidence suggests that commercial stonefish antivenom does have some detoxifying affect on lionfish venom.

Lionfish can sting you even after the fish is dead. The venom is a neurotoxin. Once the spine punctures the skin, the venom enters the wound through grooves in the spine. Fisherman have said that the sting of a lionfish is like “getting hit hard by a hammer, then injecting the bruise with hot sauce.” Its not a bad idea to wear gloves if you might encounter one. [Source: Smithsonian magazine]

Describing a lionfish sting. Susan Earle Ph.D. wrote in National Geographic, "As the pain began to spread through my hand, I tried to entertain myself by watching a graceful school of small damselfish...Within ten minutes I closed my eyes and could think of nothing but the intense, stabbing agony that was building in my finger. Only twice before had I known such pain: briefly, in a dentist's chair, and during childbirth...Tears came. I wanted to cry out, but with a regulator in my mouth...I could only remain silent...After 45 minutes my finger had swelled to nearly double its normal size, and my arm and shoulder began to ache as well. But finally, as the hour ended, the sensation began to diminish...The burnish in my finger continued for two hours, and tenderness and swelling was evident for several says."

Lionfish Characteristics

Clearfin lionfish (Pterois radiata)

Lion fish have conspicuous warning coloration with red or black stripes, and feathery dorsal fins and wide fans tipped with venomous spines. advertising their ability to defend themselves. The tails and rear dorsal and pelvic fins of some lionfish are transparent Juvenile lionfish have a unique tentacle located above their eye sockets that varies in phenotype between species.The evolution of this tentacle is suggested to serve to continually attract new prey; studies also suggest it plays a role in sexual selection.

Lionfish generally have a laterally compressed, somewhat deep body and elaborate dorsal, pectoral, and pelvic fins. The first dorsal fin contains 12 to 13 spines, the second contains 11 to 12 soft rays, the anal fin is composed of three spines followed by six soft anal rays, and the pectoral fin contains 17 unbranched, soft rays. Teeth are numerous and very small, occurring on the upper and lower jaws in densely packed bilateral clusters and in a small patch on the anterior roof of the mouth. [Source: Padgette' Steer, Animal Diversity Web (ADW) /=]

Pterois species can live from 5 to 15 years. They sense using touch and chemicals usually detected with smell and invest most of their energy in growing to a large body size early in life. This strategy allows them to grow big at a fairly young age so that they are more likely to avoid attack by predators and increase their chances of mating successfully.

Lionfish Behavior

Lionfish are primarily reef dwellers but they are also found in warm, marine water elsewhere in the tropics They tend to glide along the rocks and coral during the night and hide out in caves and crevices during the day. At night they move about in the darkness by slowly undulating the soft rays of the dorsal and anal fins. Although most of the lionfish's' feeding is completed within the first hour of night, they remain out in the open until day. When the sun comes up, they retreat to their crevices.

Lionfish sometimes cruise around upside down. When threatened they arch their head and point their dorsal fins at the aggressor, but generally they drift around the reef minding their own business and don't attack unless they are cornered. However, lionfish often have a hostile attitude and are territorial toward other reef fish. Many universities in the Indo-Pacific have documented reports of Pterois aggression toward divers and researchers.

According to Animal Diversity Web: Male lionfish are more aggressive than females. While courting, males are particularly aggressive. When an invading male lionfish enters the territory of a courting male, the agitated male will approach the invader with widely spread fins. He will then swim back and forth in front of the intruder while pointing his poisonous dorsal spines forward. Next, the breeding male will sit face to face with the intruder and tremble its spines in a way similar to when it is feeding on invertebrates. The agitated male will then shake its head just before charging at the intruder in an attempt to bite the intruder's head. This violent biting can result in the intruder having parts of its mouth torn off. However, it can also result in the aggressor becoming impaled on the spines of the intruder. If the aggressor becomes impaled it is badly stung. Nonetheless, it shakes itself loose and continues to attack the intruder until it retreats.

Lionfish communicate with vision, touch and vibrations. They sense using vision, polarized light, touch, sound, vibrations chemicals usually detected with smelling or smelling-like senses. Like other bony fish, lionfish possess sensory structures to perceive vibrations and pressure (the lateral line), chemicals (nares), and eyes that may distinguish polarized light. Communication appears to occur mainly via visual cues. If a male lionfish meets another male while hunting, the more aggressive male will turn darker in color and point its poisonous, spiny dorsal fins at the other individual who usually folds down its pectoral fins and swims away. /=\

Lionfish Prey and Hunting

Lionfish mostly prey on small fish, invertebrates, and mollusks. Skilled hunters, they attack head-first, spreading their large pectoral fins, and swallowing prey in a single motion. Lionfish fee on more than 70 marine species. Up to six different species of prey found in the gastrointestinal tracts of some specimens.

Lionfish feed most actively after sunset and in the morning.. In general, they sit is one place and feed on as many fish as possible when fish are plentiful and then it fasts when food is scarce . Their stomach that can balloon to 30 times its volume to take in food when prey are abundant. Lionfish attack with one quick gulping motion that sucks the prey into its mouth. This attack is often so fast and smooth that if the victim is among a group of fish, the other fish in the group may not even notice what happened and the lionfish can hunt the other unaware members of the group. /=\

Lionfish use their specialized swim bladder muscles to precisely control their location in the water column, allowing them to adjust their center of gravity and get the best angle to attack their prey. They blow jets of water while approaching prey, which serves to confuse them and alter the orientation of the prey so that the smaller fish is facing the lionfish. This results in a higher degree of predatory successes.

Lionfish sometimes use their colorful pectoral fins and feathery appendages to confuse and herd prey. Lionfish sometimes hunt in packs, encircling a school of bait-size fish and then taking turning turns lunging and getting a mouthful of the fish. When lionfish hunt together, one of the fish leads the attack with a small movement of one of its pectoral fins. Once its fins has been lifted, the participating both fish attack the prey mostly by biting. This kind of cooperative hunting is rare among fish. [Source: David Doubilet, National Geographic, November 1987 ┭]

Lionfish are the only species that blows water “in an effort to get prey to turn toward the lionfish before being devoured,” the Florida Fish & Wildlife Conservation Commission says. “Lionfish are stalking predators that often corral prey into a corner. They can consume prey that are more than half of their own length and are known to prey on more than 70 marine fish and invertebrate species.” [Source: Mark Price, Miami Herald, May 25, 2023]

Lionfish Predators

Aside from instances of larger lionfish engaging in cannibalism of smaller individuals, adult lionfish have few natural predators, likely due to the effectiveness of their venomous spines and the warning they display. But that doesn’t they are totally safe. Moray eels, bluespotted cornetfish, and large groupers have been observed preying on lionfish. Sharks are also believed to be capable of preying on lionfish with no negative effects from their venom. The Bobbit worm, an ambush predator, has been filmed preying upon lionfish in Indonesia. It is assumed that numerous species feed on lionfish larvae and juveniles.

According to Animal Diversity Web: Lionfish have many unique qualities to deter predators. During the day they remain in caves, mostly avoiding open waters, which keeps them hidden from potential predators. Their calm and slow moving demeanor allows them to remain inconspicuous to many surrounding animals. The asymmetrical stripes and blotches of color on their bodies allow them to blend in with the jagged, coral and polyp covered rocks in caves. Ultimately, their best and most dangerous line of defense is their venomous spines protruding from nearly all of their fins. Hawaiian turkeyfish can be considered aposematic, but not in terms of color; instead, individuals display their spines as warning to those that wish to consume them. [Source: Carlie Perry, Animal Diversity Web]

Lionfish Reproduction

Lionfish are oviparous (young are hatched from eggs) and iteroparous (offspring are produced in groups). They engage in year-round breeding. Reproduction is external, meaning the male’s sperm fertilizes the female’s egg outside her body. They employ broadcast (group) spawning, the main mode of reproduction in the sea. It involves the release of both eggs and sperm into the water and contact between sperm and egg and fertilization occur externally. The number of offspring ranges from 2,000 to 15,000. Females frequently release two mucus-filled egg clusters, which can contain as many as 15,000 eggs and float just below the surface. The average time to hatching is 36 hours. Pre-birth provisioning is done by females. There is no parental involvement in parenting. [Source: Mahya Wood, Animal Diversity Web (ADW) /=]

Female red lionfish (Pterois volitans) and female devil firefish (Pterois miles), spawn every three to 4 days year round. According to Animal Diversity Web: Although there is not a "breeding season" for lionfish, more females reach the point of maturity during the summer, consequentially increasing the number of larvae being spawned. The males, on the other hand, show no significant difference in mating ability throughout the year. [Source: Carlie Perry, Animal Diversity Web (ADW) /=]

Female red lionfish can produce 200,000 to 400,000 eggs in their lifetime. Depending on the size of the fish, females can spawn from 2,000 to 15,000 eggs every 3-4 days year-round, making them a broadcasting species. Although these fish do not breed seasonally, more females reach maturity during the summer months, increasing the number of eggs produced. While females spawn once every couple of days, males remain active daily, fertilizing multiple egg sacs even in one night. Each of these egg sacs will begin hatching in approximately 36 hours.

Lionfish Mating

Lionfish have complex courtship and mating behaviors. They are polygynous (males having more than one female as a mate at one time). According to Animal Diversity Web: Pterois species are generally solitary, but form spawning aggregations. When preparing to spawn, males become darker and more uniformly colored, as their stripes become less apparent. Females with ripening eggs become paler and their belly, pharyngeal region, and mouth become silvery white. As a result, the females are easier for the males to detect visually.

Lionfish generally use their venomous spines for defense, but during mating season males may use them to ward off other males. Fishelson (1975) observed in times of breeding that males will defend their female mate first through visual intimidation, expanding their spines to give a larger appearance. They may also attempt to bite and vigorously shake other males. If this attack is attempted, but an invading male reacts quickly by shifting their body, both fish may collide and be stabbed by each others spines. [Source: Carlie Perry, Animal Diversity Web (ADW) /=]

Courtship begins just before dark and is always initiated by the males. After the male searches out a female, he rests next to her on the substrate and looks toward the water surface while propping himself up on his ventral fins. He then proceeds to circle the female. After circling several times, the male then ascends to the water surface with the female following behind. While ascending the female will tremble her pectoral fins. The couple may descend and ascend several times before spawning.

On the final ascent the couple will swim around just under the surface of the water. The female will then release her spawn. These spawn are comprised of two hollow mucus tubes that float just below the surface upon release. After approximately 15 minutes, these tubes fill up with seawater and become oval balls two to five centimeters in diameter. Within these mucosal balls lie 1-2 layers of individual eggs. The number of eggs per ball varies from 2,000 to 15,000. As the female spawn are released, the male releases his sperm, which penetrate the mucosal balls and fertilize the eggs inside. /=\

Lionfish Young

Twelve hours after fertilization the embryo begins to form. The head and eyes become moderately developed about 18 hours post-fertilization. Eventually, invading microbes deteriorate the mucus walls and 36 hours after fertilization, the larvae hatch. four days after conception, the larvae are already good swimmers and are able to begin feeding on small ciliates. Lionfish larvae, like those of many reef fishes, are planktonic and invest most of their energy in growth early in life. Larvae settle out of the water column after approximately 25 to 40 days, at a length of 10-12 millimeters. /=\

Devil firefish (Pterois miles) undergo metamorphosis into adult fish once the larvae reach a length of 10-12 millimeters they. Although indeterminate growth (continue growing throughout their lives) for some lionfish species has not been reported, it is most often true for fish in general and has been reported for the red lionfish. The indeterminate growth rate of red lionfish is dependent on the number of other lionfish on the same coral reef. /=\

Image Sources: Wikimedia Commons; YouTube, Animal Diversity Web, NOAA

Text Sources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated May 2023

This site contains copyrighted material the use of which has not always been authorized by the copyright owner. Such material is made available in an effort to advance understanding of country or topic discussed in the article. This constitutes 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. If you are the copyright owner and would like this content removed from, please contact me.