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The lionfishes (also called turkeyfishes
or zebrafishes) are certainly some of the most recognized
of the marine fishes, likely second only to the percula clownfish.
Yet, these members of the Family Scorpaenidae are well known
around the world not only for their looks, but for their ability
to strike an unlucky victim with venom-delivering spines,
as well. The fact that lionfishes are collectively one of
the most popular aquarium-kept fishes makes the potential
for hobbyists to receive such injuries very likely. Thus,
it is a good idea to be aware of the common cause and effects
of a sting and the appropriate first aid and treatment for
such. Fortunately, while stories of lionfish stings having
horrible effects (including death) abound, and are even heard
in Hollywood movies, the truth is far less exciting. As it
turns out, a mortal sting is much more likely to come from
one of the lionfish's less conspicuous cousins.
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Figure
1. Pterois volitans - One of the most recognized
and popular fishes in the marine aquarium hobby.
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The Fishes
While all of the fishes that comprise the
Family Scorpaenidae are indeed venomous, the members of the
family can be split up into three general groups, each of
which deliver venom of differing quantity and potency. Lionfishes
(ex. Pterois spp.) are known for typically having long,
relatively slender spines, and they also have the smallest
venom glands and produce the weakest venom. The scorpionfishes
(ex. Scorpaena spp.) have shorter, but sturdier spines
and larger venom glands compared to the lionfishes, and thus
have the potential to deliver a more potent sting. However,
it is the stonefishes (ex. Synanceia spp.) which are
the truly hard-hitters. Armed with even shorter and stronger
spines, they have the largest venom glands, and can deliver
a much larger dose of far more powerful venom to a victim.
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Figure
2. Clearly visible are the venom-delivering dorsal
spines of this P. volitans.
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Lionfishes can vary in adult size from
only 4" (ex. Dendrochirus biocellatus - the Fu
Manchu lionfish) up to 15" (ex. Pterois volitans
- the Volitan lionfish), and are voracious predators that
feed on everything from small shrimps to surprisingly large
fishes. They typically have 12 to 13 elongated dorsal spines,
and also have 2 pelvic spines and 3 anal spines, all of which
have a pair of venom glands at each of their bases. However,
the fan-like array of pectoral fins, which may appear superficially
the same as the dorsal fins in structure, are not equipped
with these glands.
While the ornate, free-swimming lionfishes
are typically easy to spot, the scorpionfishes and stonefishes
typically are not. These fishes tend to have well-camouflaged
bodies and spend much if not all of their time sitting motionless
on the seafloor where they feed by ambush, as unwary prey
items get a bit too close. With this in mind, it should be
no surprise that essentially all envenomations by scorpionfishes
and stonefishes come by way of unintentionally stepping on
one that has eluded visual detection, rather than as the result
of an aggressive attack. Fortunately, both of these types
of scorpaenids are rarely, if ever, offered to hobbyists,
and I don't know of anyone that walks around in their aquarium
either. So, these two groups of fishes are not a major concern
to aquarists.
The Envenomation
Stings from lionfishes are a defensive
response, typically to being cornered or harassed in some
way, with the dorsal spines being the predominant weapon.
Lionfishes can charge at an adversary at surprising speed
considering their less-than-hydrodynamic appearance, and wield
the dorsal spines like so many tiny lances in a joust. This
happens most often during tank maintenance, when the aquarist's
attention may move away from the fish and to the task at hand.
While most fishes will typically move away from a scrubbing
arm, the lionfishes have a habit of occasionally moving away
- just enough to get a running start back at the arm. I have
been stung myself in this way, and I'll tell you that it happened
in the blink of an eye. My advice is to watch what you are
doing and don't assume that a fish you've had for a while
has somehow turned "tame", as the 12" individual
that stung me had been in an aquarium under my care for at
least two years without incident. For whatever reason, it
was "spooked" that day, and reminded me that I shouldn't
be so careless as to ignore it. Of course, the other common
way to get stung is to attempt to handle a lionfish during
transportation, introduction, or relocation, with the end
result being the same.
The mechanism of the sting is actually
rather simple. Each spine is covered with a sheath-like integumen
from tip to base, which is compressed down the spine when
the spine is thrust into a victim's flesh. The venom glands
are positioned at the base of the spine, and upon compression
of the integumen, they are basically squeezed from above and
thus release their product. The venom then travels through
thin grooves in the spine and is delivered into the puncture
wound created by the spine. As I understand it, the harder
the strike, the deeper the wound, the more compression, and
the more venom injected. Hence, light strikes can be far less
injurious than hard ones. The venom delivered is variable
in toxicity among types of lionfishes. However, in all species
the venom produced is comprised of thermolabile proteins which,
as the name suggests, are sensitive to heat.
Another aspect of a strike is the potential
to have a spine(s) broken off in the victim's flesh. Recall
that the spines of the lionfishes are relatively long and
thin, and sections can be snapped off should the victim jerk
away from an attacking fish at the moment of insertion. While
the venom may initially be the only concern, a piece of spine
left in a wound may actually be far more detrimental to a
victim's health in the long run.
The Effects
Again, while stories of death by lionfish
are common, it has been impossible for me to find a single
documented case of such after an extensive search of medical
literature. Other authors have reported the same results.
This does not mean that it has never happened, but it implies
that death by lionfish is exceptionally rare or unrecognized.
It may in fact be limited only to those victims that might
display some sort of allergic reaction, or to those that suffer
from a fatal infection related to the wound.
Conversely, in the vast majority of cases,
the predominant effects of a sting are nothing more than severe
pain and swelling (edema) in the area around the puncture.
Some victims have experienced systematic responses such as
nausea, dizziness, muscle weakness, shortness of breath, hypotension,
and headache brought on by the venom, or as a reaction to
the level of pain, or both, but that's about it. In the worst
of cases when medical treatment has been administered, some
blistering and/or tissue loss (necrosis) has been experienced
in the wound area, but this is very uncommon.
In a series of 101 documented cases of captive lionfish
envenomations in the US, the following effects were reported
(Gallagher, 2001):
92% of patients experienced local pain
60% of patients experienced edema
13% of patients experienced systematic symptoms
1% of patients experienced tissue necrosis
0% of patients experienced death
In another study of 45 documented cases
of captive lionfish envenomations reported to the San Francisco
Poison Control Center over a 5 year span, the following effects
were reported (Kizer, et al, 1985):
100% of patients experienced local pain
22% of patients experienced pain extending through the affected extremity
13% of patients experienced systemic symptoms
0% of patients experienced death
So, you should be convinced at this point
that the odds of being seriously injured by a lionfish, while
not null, are certainly slim if the wound is treated properly.
The Responses
There are several things to do if stung
by a lionfish, one of which is getting professional help.
I realize I've just pointed out that the chances of receiving
a serious injury are slim, but that's if a sting is treated
promptly and properly. Avoiding professional help, or neglecting
such an injury, can be very painful and can lead to real trouble.
Applying first aid at home can help to relieve the pain almost
immediately, but a trip to the emergency room is strongly
advised.
As far as first aid goes, you should check
to see if there are any obvious pieces of spine left in wound.
If any are present, and can be easily removed, do so with
great care. Oftentimes it may be too painful an ordeal to
remove pieces yourself, and you may need to wait until a medical
professional can take care of it. The pieces are best removed
using tweezers and a microscope anyway, and it's likely that
if you get stung, it will happen to your dominant hand. Left-handed
home surgery (or right for the lefties) sounds bad to me -
something to take into consideration. Special care should
also be taken if a piece is imbedded near a larger blood vessel,
a joint, or a major nerve, etc., in which case you can compound
the problem by attempting to do it yourself.
In the event that the wound bleeds, apply
direct pressure to help stop the flow. But, you may have to
forego this procedure if you believe you may have a piece
of spine left in the wound. Better to bleed a bit than to
unintentionally force a piece of spine further into your flesh.
The next step is hot-water therapy. The
venom is broken down very effectively by exposure to heat,
and you can therefore soak or bathe the injured body part
in water that is as hot as you can stand. This is normally
around 110° to 114° F, and should not be any hotter
as you'll risk scalding yourself and making matters worse.
Of course, the sooner you can get to a
hospital the better, and upon arrival it is important to report
exactly what kind of fish has stung you. You should not assume
that every doctor knows what a lionfish is - so explain if
necessary. Once under their care, you will likely receive
a hot-water treatment for 30 to 90 minutes, and may get a
shot of anesthetic if the pain is still severe. Some doctors
have suggested the use of a long-lasting painkiller like bupivicaine
to ease the pain, as it can be used to deaden a wound area
for hours. However, in the study of 101 cases summarized above,
97% of patients were relieved of pain by using the hot-water
treatment only. Either way, once the initial treatment is
complete, the wound should be elevated if needed to help reduce
any swelling.
While you may play surgeon and try to remove
any pieces of spine yourself, it is absolutely imperative
to make sure that any and all material is cleared from the
wound. Thus, it is highly recommended that the area be thoroughly
checked using standard X-ray techniques, ultrasound, or even
a CT scan or MRI scan. While this may seem excessive, keep
in mind that the subsequent infection of a wound can oftentimes
be far worse than the wound itself, and that leaving even
a tiny piece of a fish under the skin is a good way to get
one.
Be aware that if you should get an infection
whose effects spread into other body parts and/or systems
(bacterial sepsis), you stand a good chance of dying even
if the sting itself was not life-threatening. Therefore, in
all cases where a skin-breaking wound is caused by a marine
organism, tetanus prophylaxis (like a shot) is required if
you are not already up to date. It is well documented that
tetanus has caused many deaths following marine organism-related
penetrating wounds. Likewise, numerous other infections can
also occur in conjunction with such wounds, including those
caused by Vibrio spp.
I can't emphasize enough - be mindful of
the possibility of the after-effects of a sting. Bad stuff!
Because the potential for these complications is so high,
doctors may also use various antibiotics as part of treatment.
This is especially true if an infection appears some time
after the initial injury has occurred. Signs of infection
include, but are not limited to, redness, tenderness, red
steaks, swelling, pustulent discharge, and abnormal healing.
A Bit More
As far as scorpionfish and stonefish encounters
go, very severe injuries are indeed typical, but deaths are
nevertheless very uncommon. And, in some reports, death did
not occur until many days or even weeks after the initial
injury, leading to the belief that these fatalities were more
likely the result of complications arising from infection
of the wound. In one well-documented report of death due to
stonefish envenomation in the medical literature, it is believed
that the venom was injected directly into a larger blood vessel,
and thus was able to spread rapidly throughout the victim's
body; specially bad luck for the victim. But, in general,
chances for survival are good if timely medical treatment
is provided, even in the worst cases.
To finish, if you are a diver and you should
happen to get stung while underwater, don't get the bends
trying to surface too quickly. You'll likely be much better
off taking your time surfacing and then dealing with the wound,
rather than being placed in a decompression chamber and having
to deal with the wound inside the chamber. If you fear that
you may be suffering from symptoms of decompression-related
sickness, you must make medical personnel aware of this immediately,
regardless of the intensity of pain caused by a sting!
Stay out of trouble…
*The first aid and further medical
treatment discussed in this article have been taken from various
sources that provide information given by medical professionals.
It is in no way intended to be a substitute for professional
medical care in the event of a scorpaenid fish envenomation,
and is given strictly for information purposes.
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