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The Mystery of the
Atlantic Pterois Lionfishes 

by Anthony Calfo

For more than a few years now, people have reported seeing various non-indigenous marine fishes along the Tropical Atlantic coast of the United States of America. In most cases, they have been isolated specimens in isolated locations. In some circumstances, private homeowners would occasionally see ornamental specimens living in their quiet “backwater” canals. Other times, the exotics have been observed lingering around patch reefs, or in lagoons. The source of some of these fishes was suspected to be release from hobbyists or a rare escape of commercially-held specimens from wholesalers of imported fishes during hurricanes or severe storms. But such small numbers of fishes (usually single specimens) cannot form founding populations easily, if at all. And so, the establishment of the Indo-Pacific Pterois Lionfishes in Atlantic waters has been quite a mystery.

To compound the mystery even further, some investigators are inclined to believe that the origin of the founder population of Pterois is on the coast of North Carolina, and not Florida, as most people would expect. At first glance, this is perplexing. To begin with, Florida is the only state in America, outside of Hawai’i, that has a climate even remotely comparable to the Indo-Pacific. Moreover, Florida has an enormous industry of established trade in marine ornamental fishes: both import and export. Florida also has one of the largest state populations and, subsequently, one of the largest bases of participating saltwater hobbyists. These are more likely sources of introduced exotics.

Indo-Pacific lionfishes now appear to be established in the Tropical West Atlantic.  Photo Anthony Calfo

By contrast, however, North Carolina has a rather modest population, and a relatively weak marine hobby market. In fact, they have fewer livestock retailers and hobbyist clubs than most other states in America. The weather, although usually mild, can also be very cold in the winter, and snowfall is recorded. Thus, the statistical likelihood of Pterois establishing along North Carolina coasts seems unlikely compared to Florida. But we must consider all potential sources of a founding population of Lionfishes, beyond the obvious ones stated, before we dismiss or the theory of a North Carolina origin.

By most estimates, there is a reproducing population of Pterois lionfishes in the Western Atlantic. Their population is estimated to be numbering in the thousands. It is not even restricted to the Tropical waters, either! This may sound impossible, but it is interestingly true. The ocean currents shift in summertime with a pattern called the “Gulf Stream” that sends very warm waters from the Tropical West Atlantic north towards New York. Remarkably, species of beautiful Florida and Caribbean fishes can be seen and collected during this time of year along the northern Atlantic coasts.

Joe Yaiullo, Director of the Atlantic Marine World facility, has been collecting “Gulf” species off the coast of New York each summer for many years. I’ve known Joe as a colleague in the aquarium industry for over ten years, and I asked him recently if he’d ever seen Pterois Lionfishes in any of his collections. With an amused smile, he told a story of his first experience with Pterois species in New York waters. He had been asked to do exploratory collections to see if Lionfishes could be found locally. Upon accepting the challenge, Joe reported that within the first 30 minutes of his first collection, he netted a bucket full of juvenile Pterois specimens! He then brought them back to his facility (pers. comm. 2005) where he put them on display for education and public awareness. These specimens were collected merely by wading into shallow water and captured with nets. [note: Atlantis Marine World is a fabulous facility for tourists, aquatic scientists and marine hobbyists alike, which includes an 80,000 liter coral reef display that is magnificent! For more information on the Internet, visit]

Pterois is a formidable predator with patience and persistence.  Photo Anthony Calfo

Sightings of Pterois Lionfishes to date have been reported along most of the Atlantic coast of the USA and from Bermuda in the South to New York in the North. One of the first specimens captured by a fisherman with hook and line was off the coast of North Carolina; the specimen was approximately 43 cm long and over one kilo in weight. Presently, removal of this established exotic fish seems impossible. There have been concerns voiced about public safety, regarding swimmers and divers getting stung by members of this venomous genus, but most experts agree that these are very small risks. No fatalities have been recorded from Pterois envenomation here, and the sightings of specimens at large have mostly been offshore and in deep water (over 20m). The biggest concern overall is the potential reduction or elimination of native species by this non-native predator. While reports of Pterois in the Atlantic have occurred for perhaps ten years or more, very little study has been done to estimate the impact of the exotic or it’s potential ramifications. Experts are not only unsure about what, if anything, to do about the presence of these fishes… but they cannot even agree on the specific source of the introduced specimens!

While some scientists and investigators would like to ascribe the establishment of exotic species to hobbyist release of pet specimens, the practical reality as I see it makes this a highly unlikely explanation. To begin with, it seems implausible that enough individual hobbyists would coincidentally decide to release enough specimens near enough to each other on a reef to found a colony of exotics. Furthermore, unwanted specimens are often overgrown, unfit from a captive life, and generally suffering from inadequate food (e.g. - thyroid problems from iodine deficient foods) and poor exercise in small home aquaria. They simply lack conditioning to find and compete for food on a wild reef, not to mention avoiding the perils of would-be predators. And even if they acclimated to the wild waters sufficiently… the odds of so few specimens finding each other on a reef, at the right time (s) to spawn, seems small. Then, the small batches of larvae from a successful spawn would have to survive on alien plankters in alien currents on an alien reef. Beyond that, enough of these larvae would need to successfully settle out and then grow to maturity in such (initially) small population numbers to then find each other some years in the future to spawn with hope for continuation. The statistical likelihood of a favorable outcome to individual releases of pet fishes being the origin of these exotics is slight, to say the least, in my opinion.

Caution: Pterois volitans can quickly outgrow small home aquaria! Photo Anthony Calfo

Another theory argued is that dive or tourism merchants seeded isolated patch reefs with imported batches of these fishes to improve revenue for their sites and attractions. As preposterous, if not nefarious, as the notion sounds, some significant aspects of the appearance of Lionfishes in the Atlantic do not exclude this possibility. In fact, there may be great credibility to the assertion. Investigators have complained that (some, not all) dive operators have been uncooperative with scientists seeking information on where to find Lionfishes on remote reefs. One could speculate that the merchants are protecting their “discovery”, if not their “investment.” As a possible founder source, it is at least consistent with early appearances of Pterois in North Carolina and beyond: most observations of the fish to date have been far offshore on isolated reefs at depth. These sites are miles away from the coastal waters where a hobbyist would likely spill and release a pet fish. And the likelihood of such poorly conditioned (captively grown) fishes swimming through vast stretches of open ocean to reach offshore reefs safely seems rather unlikely, compared to the chances of adults simply being seeded directly (by boat operators) on an isolated reef, or settling from larvae released or dispersed.

The release of pet fishes likely explains the appearance, albeit rare in number, of Indo-Pacific angels or tangs in Florida waters.  Platax orbicularis (L)  Photo by Robert Fenner  Zebrasoma Scopas (R).  Photo by Anthony Calfo.

This notion of larvae as the source of introduction is also quite interesting. One might wonder, initially, where would enough larvae come from to seed a reef to found a breeding population? How could eggs or larvae from the Indo-Pacific survive the trek to the Atlantic coast of America? On further consideration, though, carriage by boat with ballast water seems to be a plausible explanation. In fact, other fishes and invertebrates have been transported as contaminants this way. Notably, the egg masses of Lionfishes are sticky, durable and float. By this nature, they can easily come into concentrated contact with surface sailing boats. With this theory in mind, we can also see that North Carolina is home to some of the largest and busiest ports and shipyards in America. This situation is bolstered tremendously perhaps by the presence of naval ships. The unfortunate political realities in the Middle East have additionally spurred a number of military vessels to travel to the Indo-Pacific, Persian Gulf, etc. The possibility of piscine contaminants with many thousands of gallons of water being repeatedly transported by boats from afar is possible here, and is yet another remarkable theory

The Indo-Pacific Chromis viridis has been spotted in Atlantic waters.  Photo by Anthony Calfo

For what its worth, I honestly don’t have a strong opinion on what the principal source of Pterois was to establish a breeding population. All of the theories presented to date are equally possible and equally unlikely to me at the same time. Could hobbyists really be the source of the foundling population? Yes… I do believe it is possible. Especially if we have underestimated the span of time that occasional releases from private owners of unwanted fishes has occurred. Pterois spp. are indeed long-lived and obviously better protected (venomous spines) than most other fishes. Their establishment is not so surprising, whereas small numbers of other notable exotic species have been observed only sporadically through the years, such as Pomacanthid angelfishes, Acanthurid surgeons and tangs, and various small fishes such as Pomacentrid damsels. There is even a concern about the increasing appearance of Pacific Ephippid spadefishes (AKA “batfishes”) schooling with Atlantic species: the worry is that they will interbreed. Still, it is remarkable to me that enough specimens of any exotic can survive any of the proposed theories of introduction in the dynamic Tropical West Atlantic ocean to establish a colony. And whether you tolerate or dislike the reality of exotic introductions, it is at least testimony to the hardiness and adaptability of some amazing and beautiful reef fishes.

Resources and Bibliography:

Dr Robert Goldstein, “Lionfish in the Western Atlantic,” Seascope, Volume 21, Issue 2, 2004


MARINE ORNAMENTALS (conference) 2006 February 13-16, 2006 Las Vegas, Nevada for discussions with academics and industry professionals of aquatic science.

"Characterizing the US Trade in Lionfishes"          10/28/19
Contact: Dr. Kevin Erickson (
Dr. Junda Lin Memorial Fund for Publishing Open Access Marine Aquarium Research website HERE (
For Release on October 28, 2019
MASNA's Q3 2018 Open Access Memorial Fund Article now freely available to the public.
MASNA is proud to announce that the Quarter 3, 2018 publication funded by the Dr. Junda Lin Memorial Fund for Publishing Open Access Marine Aquarium Research is now freely available to the public as an open access article. 2017, MASNA introduced the Dr. Junda Lin Memorial Fund for Publishing Open Access Marine Aquarium Research with the goal to off-set the cost to students of publishing research as open access articles in order to promote the spread of scientific ideas to not only scientists, but to anyone who is interested in the research, by making it freely available.

Dr. Junda Lin was a Professor of Biological Sciences at the Florida Institute of Technology and the Director of the Institute for Marine Research (IMR). Dr. Lin’s Lab focused on the development of aquaculture technology for marine ornamental species to offset and replace wild collection. Dr. Lin’s lab studied the basic biological processes of several shellfish and fish species, evaluated their aquaculture potential, and developed cultivation technology.

Rather than the traditional scientific publishing scheme where the reader of the scientific article incurs a cost to access the article, open access articles charge the author a fee when the article is accepted by the publisher, resulting in scientific literature that is freely available to the entire world.

Therefore, the Dr. Junda Lin Memorial Fund for Publishing Open Access Marine Aquarium Research is a fund sponsored by individuals, aquarium clubs, businesses, and universities that provides students with a financial offset to the costs of publishing a scientific article as an open access article. More information on how to apply and the donation link can be found here:

Our 2018 Q3 recipient is Tim Lyons, M.Sc, conservation scientist based out of the New Mexico BioPark Society in Albuquerque, New Mexico.

Tim is the primary author of the paper entitled “Characterizing the US Trade in Lionfishes (  id=10.1371/journal.pone.0221272&utm_source=Public+BOD+Email&utm_campaign=902484607a-Junda+Fund+q3+2018_COPY_01&utm_medium=email&utm_term=0_684126d033-902484607a-457263653) ”, which was published by PLoS ONE in August of 2019. In his original research article, Tim and his coauthors identify the volume and diversity of Lionfishes exported from source countries, imported into the United States, and ultimately lionfish availability in retail settings. This information is intended to provide managers and policymakers with a proactive evaluation of Lionfishes traded within the country that are closely related to the highly invasive Red Lionfish in the Gulf of Mexico and the Caribbean. Together with character trait evaluation and rapid risk screening protocols, these data can reveal potentially risky species that may present an invasion threat if released into the environment.

Tim summarizes the importance of this research here:

“Invasive species continue to have significant detrimental effects on local ecosystems, and they remain one of the most homogenizing forces on global biodiversity. Eradicating or slowing the spread of introduced species once they establish can be extremely difficult. Environmental damages and control programs for invasive marine and freshwater fishes in the U.S. cost managers and stakeholders an estimated $5.4 billion each year.

The global trade in marine ornamental species supports collector, wholesaler, and retailer livelihoods, and can produce conservation benefits through public exposure and outreach. However, the global trade in these species is not without its drawbacks, including the potential introduction and establishment of non-native species resulting from intentional or unintentional release. While the majority of these one-off introductions are benign, others, such as the introduction of red lionfish into coastal waters off southern Florida, have had major, long-lasting impacts on native reef communities.

Given the sheer volume and diversity of the marine ornamental trade, evaluating the risk of every species that may potentially be introduced into a non-native range is both cost-prohibitive and unfeasible. However, it is possible to evaluate the risk of species traded that share common characteristics to known invaders. This information can be used to inform proactive management approaches, and ultimately reduce or prevent the number of risky species that get introduced.

We used federally and state collected trade data on Lionfishes to draw the following conclusions: The marine ornamental trade is a potentially strong introduction pathway for just two species of Lionfishes, namely the Red Lionfish Pterois volitans and the Zebra Lionfish Dendrochirus zebra. The trade is a moderate to very weak pathway for all other species of Lionfishes that can be found in the trade. Lionfish import is highly concentrated at the port of Los Angeles, and most specimens originate from the Philippines and Indonesia. Retail surveys indicated a much more limited diversity of Lionfishes available to hobbyists than previously thought, especially when compared to stock lists provided by online vendors.

These data have several implications. The first is that there is likely significant lionfish mortality occurring from the time lionfish enter the country to the time that they are available in retail aquarium stores. Second, our analysis suggests that broad, blanket regulations on the trade of Lionfishes at the genus level, such as those imposed by Florida state regulatory agencies, may be unnecessary. Finally, our data suggests that the riskiest species of lionfish from a trade volume perspective is still the Red Lionfish. While this species is already established in Florida waters, the vast number of species in trade are still imported from the Indo-Pacific. Therefore, secondary introductions have the potential to introduce new novel genes or traits that strengthen the impacts of the current lionfish invasion in the Atlantic Ocean.”

Scientific research has historically been published and distributed by for-profit companies that require readers to pay to access content, comprising a 19.6 billion dollar industry that results in inaccessibility for most hobbyists. However, open access publishing has been gaining traction in recent years. Project S, an initiative that promotes specific open-access publishing requirements for scientific research funded through public grants, has recently been endorsed by several international governments. Additionally, research institutions have begun terminating long-standing subscriptions to for-profit journals, and many independent researchers have taken an active stance on information dissemination by opting to publish in open-access formats. MASNA fully supports open-access publishing, and firmly believes that research relating to aquarium science should be available to anyone who wishes to read it. For more details on recent open-access publishing developments, read HERE
( .

MASNA would like to thank the donors that have contributed to the Junda Lin Memorial Fund thus far. Open-access publications allow the rapid dissemination of research to the non-scientific public that would otherwise not be able to access this information.

The modern marine sciences increasingly recognize the importance of informed hobbyists and citizen scientists in data collection, volunteer work, and in their ability to drive changes in public outlook and policy. MASNA welcomes donations from any organization or individual who shares the belief that advancements in science should be freely available to the general public, and those that support MASNA’s mission to encourage the sustainability and ethical growth of the marine aquarium industry through the education of its members and the wider hobbyist community.

About MASNA:

MASNA is a 501(c)(3) non-profit organization composed of marine aquarium societies, individual hobbyists, and industry partners from North America and abroad, totaling several thousand individuals.

MASNA’s goals are to:
* Educate our members through online and published material, the MACNA conference, and other sanctioned events.
* Assist in forming and promoting the growth of clubs within the hobby while ensuring a sustainable future for the marine environment.
* Support the efforts to eliminate abuses in collecting and transporting marine organisms through education, assistance, and encouragement.
* Encourage the ethical growth of the marine aquarium hobby and support captive breeding/propagation efforts.

More at
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Click here to read the article (

Q from a Scientist - Caribbean Sharpnose Puffers Nipping Off Fish Spines?   8/22/11
Hi there,
<Hello Merritt here.>
I'm a graduate student doing some work on lionfish down in the Caribbean and witnessed an unusual interaction between invasive lionfish and a Caribbean Sharpnose Puffer (Canthigaster rostrata) that I'd be curious to hear your take on!
<Great! Helping with the lionfish invasion are you.>
During the capture, handling, and tagging of lionfish that makes up the bulk of my project, the skin covering the venomous dorsal spines of lionfish are often tugged down as they poke through the collection nets. On one occasion, after one such fish was released from its bag and was sitting on the reef recovering, a Sharpnose puffer came over and began biting at the exposed portion of the dorsal spines. On fish re-sighted after tagging, these exposed spines are often shorter and blunted, as though the exposed end has been bitten off. I was just wondering if your team has had any experiences with Sharpnose puffers biting off fish spines in the past, and on what might cause this behavior?
<Actually I have personally witnessed puffers of many species exhibiting this behavior in an aquarium. I can only assume in an aquarium that the behavior is either one of territory defense or two them being typical puffers.>
I know they're known for biting in close quarters, but this didn't look like a territorial encounter as the puffer looked more like he was grazing or investigating a snack than trying to drive the lionfish off. I wondered if there's any nutritional benefit to puffers from nipping fins or spines that might explain this?
<None that I know of.>
I've benefited from the wisdom of WWM many times before, and recognize that for many of the less-studied marine ornamentals, hobbyists probably know more about behavior than academics, so I look forward to hearing what you think. Thanks a million!
<From what I have seen puffers tend to be very curious creatures and tend to bite things/objects to figure out what they are. Others will just pick on tank mates (especially lionfish) by nipping their fins and/or harassing them until the fish is removed or dies. I will assume this observed behavior to be of curiosity and obnoxiousness that makes up a puffer personality than for nutritional benefit. Good luck on your research and hope that you find a solution to the lionfish invasion. Merritt>
Natascia Tamburello
MSc Candidate
Tropical Marine Ecology Lab
Department of Biological Sciences
Simon Fraser University


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