Aquarists were first attracted to lionfish as pets for their bright coloration, beautiful patterns, and interesting body shape. Fishkeepers soon found out that lionfish are also hardier than many of their saltwater counterparts and are not picky eaters, further cementing the lionfish’s popularity. However, lionfish quickly became notorious for another reason: they are the deadliest pet fish. Their powerful venom and long-lasting sting pose serious dangers to pet owners, especially when combined with the lionfish’s natural aggression.
Lionfish Are Venomous
Lionfish rank among the most venomous sea creatures and are made even more dangerous due to their alluring beauty, which has tempted many aquarists to keep them as pets. One of the most striking features of the lionfish is their long dorsal spines, which spread out along their back and tail. But these distinctive spines are actually venomous: they contain a neuromuscular toxin and acetylcholine.
There are approximately 40,000-50,000 cases of lionfish sting incidents annually, surpassed only by stings from stingrays. The number of lionfish kept as pets and the resulting proximity greatly contributes to this high number, which would otherwise be lower and mostly limited to ocean divers. Since stingrays are rarely kept as pets, lionfish can be definitely ranked as the deadliest pet fish by sting incidents alone.
The least serious symptoms of a lionfish sting include sweating, headaches, nausea, and swelling. More serious symptoms of a lionfish sting include respiratory issues and distress, loss of consciousness, and even muscle paralysis. Symptoms typically escalate if not treated rapidly after the initial sting incident. The lionfish’s sting is also dangerous due to the duration of the pain. Symptoms can last for days, even with medical attention.
Therefore, every interaction with a pet lionfish is dangerous: feeding the fish, cleaning the tank, and even changing décor are all potentially hazardous.
Lionfish Stings Are Difficult to Treat
Anyone stung by a lionfish should seek medical attention immediately. Time is of the essence when treating lionfish stings since symptoms can rapidly progress and cause serious medical conditions, such as pulmonary edema. However, even with treatment, the effects of a lionfish sting can still be long-lasting and difficult to resolve.
One of the most common treatments involves a hot water bath with water kept around 114 degrees Fahrenheit. However, this bath must be no scalding: if the water is too hot, it could actually exacerbate symptoms. While this treatment method could be recreated at home, it’s only the first of several steps to address lionfish stings. Individuals should also be treated with a non-steroidal anti-inflammatory drug (NSAID) and receive a tetanus prophylaxis—e.g., a tetanus vaccine. This means that if you are stung, you will need to seek hospital treatment instead of just handling the symptoms at home.
Children are at an especially high risk of serious symptoms compared to adults due to the higher venom ratio to body mass. The appearance of a lionfish and near-hypnotic movements when at rest may be attractive to kids. Additionally, aquariums typically have minimal to no security measures and are prominently featured in the home, such as in the living room. This means that kids could climb on nearby pieces of furniture (a couch, a chair, a table, etc.) to reach into the tank.
Lionfish Are Aggressive Pets
Although there are benefits of saltwater aquariums, even enthusiasts will readily admit that the delicate dispositions of many saltwater fish can be daunting. But lionfish have the opposite problem: they are incredibly hearty and have an aggressive temperament that makes them difficult and dangerous to keep.
In the wild, lionfish typically hunt by expanding their fins and spines outward and forward, corralling prey until it is cornered. Lionfish quickly adapted this hunting pattern to the aquarium and use the same technique to trap prey (or your hands) against tank walls and corners. Lionfish are also surprisingly agile, despite their larger size (they can grow up to 15 inches long). While they often float when at rest, they can charge quickly when motivated.
Feeding time is also hazardous. The frequency of meals for pet fish will vary by species, by lionfish in particular have huge appetites. Amazingly, a lionfish’s stomach can actually expand up to 30 times its regular size in order to pack in as much protein as possible. Even juvenile lionfish eat so much that many owners are unprepared. Incidentally, this also means that lionfish must be kept alone: they will eat any and all tank mates.
Lionfish Don’t Remain Pets
Lionfish are popular aquarium pets and prized among the saltwater trade for their show-stopping appearance. But lionfish are just a threat to their owners: they’re also a threat to native species when released into local waterways.
Lionfish that grow too big for their tanks (or too dangerous to their owners) are released into nearby oceans. In these new environments, lionfish have flourished and are now classified as an invasive species. Lionfish have spread across North and South America along the east coast, as far north as New York state and as far south as lower Brazil. The lack of any natural predators in these new waters also contributes to the quickly-spreading lionfish invasion.
Although lionfish are from the Indo-Pacific, they have demonstrated extreme adaptability and are able to thrive in a variety of environments. This is good news for lionfish, but bad news for local ecosystems and native species. Lionfish are also categorized as the first exotic species to invade coral reefs.
Lionfish are opportunistic predators with large appetites and no dietary preferences, which have wide-spreading effects:
- Lionfish often outcompete other fish for limited food resources, destroying local diversity and native species.
- Lionfish often target species that are critical for coral reefs, therefore inadvertently also killing local reefs.
- Lionfish deplete local fish populations, negatively impacting economies that are dependent on fishing or marine tourism.
Lionfish can be eaten and are even considered a delicacy in some areas, which is one way to help control the lionfish population. But unfortunately, the market demand for lionfish as a food is far below the demand for these fish as aquarium pets. The import of lionfish as pets (which are then released into oceans) and the breeding habits of wild lionfish means that this invasive species continues to quickly expand.
For now, the greatest contribution that aquarists and pet owners can make to solve this problem is to abstain from buying a lionfish as a pet. For those that may already have a pet lionfish, keeping the fish in captivity and taking all possible safety precautions is the best option.
