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Continuing the theme of the November issue
on venomous fishes, I'll be discussing a portion of the family
Scorpaenidae. Also called Scorpionfish, these deadly predators
make fantastic displays in small aquariums dedicated to their
care. However, keeping these unusual fish is not in the best
interest of most hobbyists, as I hope to make clear in this
month's column.
Meet the Family
Scorpaenids are well represented throughout
the world's oceans; however, relatively few species are located
within the warmer water areas, which supply most of the marine
ornamental fish for aquarists. For information on some of
the many scorpaeonids found in cooler waters, see this month's
column
by Dr. Ron Shimek. Nearly 400 species comprise the family,
divided amongst the 45 genera (Eschmeyer, 1986). Most important
to hobbyists are the Scorpionfishes, Devilfishes, and Stonefishes.
Lionfishes are in a subdivision of the family Scorpaenidae,
the subfamily Pteroinae. For information on the care of Lionfishes,
please refer to this month's feature article
by Dr. Frank Marini.
All Scorpaenids are equipped with a large
mouth, capable of swallowing prey over half their own body
length. Spines are present on the gill plate and head, though
these are not the spines hobbyists need to be concerned about.
The thick dorsal, pelvic, and anal spines should gather the
attention of the caretaker, as these are the spines capable
of delivering a powerful, painful, and possibly deadly sting.
For more on the sting of Scorpionfish, please view this month's
feature article
by James Fatherree, and the note
by Sandy Shoup personally describing an envenomation.
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Scorpaena
brasiliensis in a home aquarium. From this photo
it should be obvious why Scorpionfish can swallow prey
over 1/2 their size. Photo courtesy of Chris Smallridge.
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Many Scorpaenids have the ability to shed
the outermost skin layer, the cuticle. Because of their sedentary
lifestyle, it is not uncommon for algae or other pests to
grow on these fish. The shedding benefits the fish by removing
any attached algae, cyanobacteria, and even parasites. There
does not appear to be a set schedule to the behavior, though
we know some Scorpaenids shed more often than others (Eschmeyer,
1986).
In the Wild
As the title of this column implies, many
Scorpaenids, particularly the Scorpionfishes, have a remarkable
ability to blend into their surroundings. One advantage to
their camouflage is that it assists in prey capture. Often,
herbivorous prey will be attracted to the Scorpionfish and
their encrusting algae. Other times, the encrusting algae
can appear to be a "safe-haven" to passing-by fish
and crustaceans. Regardless of the attraction, it is often
a fatal one. The unfortunate prey rarely has a warning, as
the attack of the Scorpionfish is lighting fast. The Scorpionfish
creates a vacuum by quickly opening their jaws, sucking the
prey into the awaiting mouth of the predator. Individuals
within one genus of Scorpaenids, the Stonefish, have been
reported to complete the vacuum-style attack in as little
as 15 milliseconds (Michael, 1998).
Scorpionfish habitat varies greatly amongst
species according to the camouflage. As examples, some members
are best suited to mud bottoms, while others have camouflage
that renders them unnoticeable amongst Pocillopora
spp. corals. Generally speaking, for any given terrain in
the shallow-water tropical oceans, one or more Scorpionfish
have adapted to it and perfected the art of camouflage within
it.
Scorpionfish are generally solitary in
nature, except during courting and mating when a pair may
be located. Groups larger than a pair are rarely found. An
exception to this is found in the Leaf Scorpionfish, which
commonly occurs in groups of three. Fighting does occur between
conspecifics, though scientists are not sure if they are defending
their territory or their mates.
Like many venomous animals, Scorpionfish
may have brilliant color warning. However, unlike many venomous
animals these colors are not on permanent display. After all,
such a display would make their camouflage pointless. Using
a behavior known as "flashing," many Scorpionfish
have the ability to display their colors when needed, such
as when a predator is nearby. Their colors are often found
on the inner surface of their pectoral fins. Some species
also have brilliant colors on the skin within their jaw structure
that can be exposed when the fish opens its mouth. This serves
as an effective warning defense for approaching conspecifics.
In the Home Aquarium
Captive care of Scorpionfish is rather
easy, assuming the hobbyist meets a few basic requirements.
First and foremost is feeding. Often, live foods will be required
to entice newcomers to eat in a captive environment. Although
commonly employed as a suitable live food source, frequent
feedings of goldfish should be avoided. A diet of goldfish
tends to lead to a thiamin deficiency in Scorpionfish, which
often results in death from loss of nervous system coordination.
Other complications derived from a steady diet of goldfish
are a lack of marine-based HUFA, excessive fat, and ammonia
toxicity (Marini, pers. comm.). Instead, the hobbyist should
concentrate their efforts on getting a recently acquired Scorpionfish
to accept prepared foods. Knowing the natural foods of a particular
species is the first step in proper nutrition, and in finding
suitable prepared food substitutes. Some Scorpionfish eat
strictly fish, while others may eat only shrimp or crabs.
Still others may accept just about anything that moves. Saltwater
"silversides" maybe the best substitute for those
requiring fish prey, while prawns are obviously the first
choice for those that prefer shrimp. Initially, efforts to
dupe the Scorpionfish into believing that the prepared foods
are actually alive is the difficult part. The method most
commonly used is to impale the dead fish or shrimp on a stick
of some sort, such as a chopstick, rigid airline tubes, or
thin acrylic rods. The next step is for the hobbyist to do
his/her best job of making the prepared food appear alive
by shaking or wiggling the stick that the food is impaled
upon near the Scorpionfish. When feeding attempts during the
day fail, try feeding at night. Most Scorpaenids are nocturnal,
so feeding at night will be more natural.
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Rhinopias
eschmeyeri, possibly the plainest Rhinopias
sp. having almost a complete lack of body camouflage.
They can be found in light blue, yellow, orange, red,
and even lilac color variations. Photo courtesy of Frank
Marini.
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The proper sized aquarium to house Scorpionfish
does not need to be large. Some of the smaller members of
the family can be housed in a 20 gallon tank, while a 75 gallon
would do an adequate job of housing one of the larger species
of Scorpionfish, or possibly several smaller Scorpionfish.
More important than the overall size is the decoration used
to recreate or simulate their natural habitat. A hobbyist
considering a scorpionfish should research the habitat requirements
for that species. Some will require plenty of caves, while
others will require an open sandbed or even mud.
Very few tankmates can co-exist with Scorpionfish
because most will be considered food. Less commonly, some
fish may confuse the Scorpionfish with food of their own.
Surgeonfish, Rabbitfish, and even Angelfish may occasionally
pester Scorpionfish, mistaking the fish for algae or even
sponges. Scorpionfish may also be a problem in a tank with
corals. Due to their sedentary lifestyle, it is possible that
a Scorpionfish may choose a particular coral as a prime territory
and the continued presence of the fish may cause injury or
death to the coral.
Compatibility
chart for members of the family Scorpaenidae:
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Fish
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Will Co-Exist
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May Co-Exist
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Will Not Co-Exist
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Notes
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Angels, Dwarf
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X
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Will be consumed.
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Angels, Large
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X
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Will be consumed. Large individuals may harass Scorpions.
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Anthias
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X
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Will be consumed.
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Assessors
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X
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Will be consumed.
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Basses
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Batfish
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Blennies
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X
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Will be consumed.
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Boxfishes
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X
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Large individuals may harass Scorpions.
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Butterflies
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X
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Will be consumed. Large individuals may harass Scorpions.
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Cardinals
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X
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Will be consumed.
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Catfish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Comet
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X
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Will be consumed.
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Cowfish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Damsels
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X
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Will be consumed.
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Dottybacks
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X
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Will be consumed.
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Dragonets
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X
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Will be consumed.
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Drums
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X
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Will be consumed.
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Eels
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Filefish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Frogfish
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X
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Will be consumed or may consume the Scorpionfish.
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Goatfish
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X
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Will be consumed.
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Gobies
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X
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Will be consumed.
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Grammas
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X
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Will be consumed.
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Groupers
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Hamlets
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X
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Will be consumed.
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Hawkfish
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Jawfish
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X
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Will be consumed.
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Lionfish
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X
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Will co-exist provided they are unable to swallow each
other.
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Parrotfish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Pineapple Fish
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X
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Will be consumed.
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Pipefish
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X
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Will be consumed.
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Puffers
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Rabbitfish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Sand Perches
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X
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Will be consumed.
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Scorpionfish
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X
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Species dependant. Only try to mix equal-sized specimens.
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Seahorses
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X
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Will be consumed.
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Snappers
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Soapfishes
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Soldierfish
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X
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Will be consumed.
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Spinecheeks
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X
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Will be consumed.
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Squirrelfish
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Surgeonfish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Sweetlips
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Tilefish
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X
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Will be consumed.
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Toadfish
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X
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Will be consumed or may consume the Scorpionfish.
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Triggerfish
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X
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Will be consumed. Large individuals may harass Scorpions.
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Waspfish
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X
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Assuming it is larger than the Scorpionfish, it may
co-exist.
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Wrasses
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X
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Will be consumed. Large individuals may harass Scorpions.
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Note:
While many of the fish listed are good tank mates for Scorpaenids,
investigation should be done to assure peaceable co-existence.
Additionally, some of the fish mentioned above are better
left in the ocean or for advanced aquarists.
Almost as important for the success of
scorpionfish in an aquarium as the captive care requirements
is that hobbyists find enjoyment in the care of Scorpionfish.
Hobbyists searching for an active fish, brightly-colored "showstoppers"
or desiring a tank filled with other fish, shrimps, or crabs
should skip this family of fish. In contrast, the hobbyist
looking for unusual fish will enjoy keeping fishes from this
group. However, because these fish are venomous and potentially
dangerous, they must be considered carefully before purchase.
I recommend that hobbyists with allergies to bee stings and
those with children or other people that may put their hands
in the tank for whatever reason avoid keeping any Scorpaenid
fish.
Captive Reproduction
Captive reproduction of Scorpionfish has
not yet been reported to date, and breeding attempts have
been unsuccessful. In fact, very little is known about their
reproduction in the wild. For most Scorpaenidae, fertilization
of the eggs occurs outside the female body, often times in
a large, floating, and gelatinous mass (Coral Realm). Prior
to the fertilization, a short mating dance occurs which involves
non-destructive fin nipping, gill cover flaring, and side-to-side
rocking, Often, the male's color will intensify. Mated pairs
are not monogamous (Marini, pers. comm.).
Meet the Species
Most of the Scorpionfish that are regularly
available to the hobby are part of the subfamily Scorpaeninae.
Within this subfamily are roughly 15 genera, and possibly
over 150 species. The genus Taenianotus, or the Leaf
Scorpionfishes, including the popular Taenianotus triacanthusare,
are potentially suitable species for aquariums for several
reasons. First, they can be housed in very small aquariums,
a 20 or 30 gallon tank can adequately hold a pair or trio
of these fish which are usually less than four inches in length.
Second, they usually like to perch on rocks or caves out in
the open and can thus be observed easily by aquarists. Third,
they come in a virtual rainbow of colors: red, maroon, pink,
yellow, tan, brown, and even black specimens are available.
The difficulty in keeping these fish, as with other family
members, is getting them to accept appropriate prepared foods.
The hobbyist should start with live ghost shrimp, and slowly
wean them to frozen/thawed Mysis shrimp, if possible.
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Taenianotus
tricanthus, a yellow variant is pictured here. These
fish do best when housed in pairs or even trios. Care
should be taken to keep water flow to a minimum, as
it prefers areas protected from currents. Photo courtesy
of Jeff Rosenfeld of The
Vibrant Sea.
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Another popular species for the aquarium
trade is Scorpaena brasillensis, or the Orange Scorpionfish.
Don't let the common name mislead you; they come in several
colors, including orange, yellow, red, and brown. They can
become large, reaching over 9" in length. Their main
prey in the wild is shrimp and various other crustaceans,
and usually they have no problem accepting this in the home
aquarium, but they do accept prepared fish in the captive
environment if the hobbyist has trouble locating other foods.
They are best housed in aquariums 30 gallons or larger containing
plenty of hiding spaces as well as macro algae, as they are
most often encountered in the wild in front of, or on, patches
of macro algae.
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Scorpaena
brasiliensis is common around the tropical coast
of the USA, and is probably the most common Scorpionfish
found in the hobby. Photos courtesy of Frank Marini.
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Some of the stranger Scorpaenidae are the
Seagoblins, Inimicus species. This genus comes from
one of the subfamilies of Scorpaenidae, the Choridactylinae.
Two major differences separate them from the rest of Scorpaenidae.
First, they have two pectoral rays that have the appearance
of claws. Second, they have eyes that rest very high on the
head. Both of these differences aid the fish in capturing
prey. Individuals of Inimicus species like to bury
themselves in sand or mud (and thus an open sandbed or mud
should be provided deep enough so the fish can bury into it)
with only their eyes, dorsal fin, and two front pectoral rays
exposed. The eyes, being located high on the head, allow it
to bury deeper, and the "claws" assist in lunging
forward to capture the prey. In the aquarium, these fish adapt
to prepared food fairly well and can initially be coaxed to
feed on ghost shrimp, later weaned onto thawed Mysis
shrimp, and finally onto various other prepared foods. If
the fish are healthy, they fare reasonably well in the home
aquarium, but be aware that they are often harassed by other
fish that view their tassled flesh as potential food. Much
like wrasses in the genus Macropharyngodon, Seagoblins
have a tendency to be injured during shipping. The lack of
sand in the shipping bags causes undo stress to the fish,
and, as a result, they usually injure their lower jaw during
shipping. Shipping with an inch or two of sand would allow
the fish to bury themselves and thus help eliminate stress,
and the subsequent damage caused by the undue stress. Be cautious
and inspect the lower jaw when purchasing.
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Inimicus
didactylus in a home aquarium. Note the large eyes
located high up on the head, and the two rays that look
simliar to claws. Also notice the up-turned mouth. All
of these attributes aid in capturing prey when buried
underneath an inch or two of sand. Photo courtesy of
Frank Marini.
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Another
photo of Inimicus didactylus. This time note
the pelvic fin on the right. Though not fully opened,
you can begin to see the coloration within the fin that
allows it to "flash" for defense. Photo courtesy
of Frank Marini.
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A
nice shot of the exposed venomous dorsal spine on Inimicus
didactylus. Photo courtesy of Frank Marini.
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Choridactylus
sp. giving
us a great view of the two pectoral rays used in crawling
along the sandbed or for capturing prey. Photo courtesy
of Frank Marini.
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For the collectors of rare and extremely
expensive fish, individuals of the various Rhinopias
species, also in the subfamily Scorpaeinae, are sometimes
available. Hobbyists that are willing to pay the $2000 US
price tag for these fish are then owners of some of the most
exotic looking fish on the planet. Their dermal appendages
are amongst the most extravagant of all marine fish, rivaling
only the Ghost pipefish of the family Solenostomidae. Care
for them is extremely similar to that required for other Scorpionfish.
In fact, they often adapt to prepared foods easier than some
other Scorpaenids. Most Rhinopias species live within
or near macro algae, and will make a faster transition to
aquariums containing macros.
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The
extremely rare and beautiful Rhinopias aphanes.
Would you pay $2000+ for this fish? Photos courtesy
of Dustin Dorton of Aquarium
City.
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Close relatives of the Scorpionfish, and
often considered as members of that family, are the Waspfish.
They were, in fact, originally classified as the subfamily
Apistinae of the family Scorpaenidae. They have since been
elevated to the family Terrarogidae. This family contains
11 genera and 35 species. Although they are not regularly
imported for the aquarium trade, the care of these species
is similar to that required for the true Scorpaenidae. As
adults, they barely reach 3" in length, and spend the
majority of their time amongst macroalgae and sponges. Their
main diet consists of worms, small fish, and even small crustaceans.
Like Scorpionfish, Waspfish are primarily nocturnal, and offering
food at night may encourage a feeding response, if required.
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Note
the white patch on the face of Paracentropogon longispinus.
This white face is common amongst Paracentropogon
spp. These little devils can be found on mud flats from
south Australia to the Philipines. Photo courtesy of
Frank Marini.
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In Conclusion
For those hobbyists looking to obtain the
odd fish, Scorpionfish may fit your desires. Their hardy nature,
small tank requirements, and ability to resist most diseases
make them great choices for species-only aquariums and newcomers
to the hobby. However, please use caution when handling these
fish, or when working in their tank. One mistake will be painful,
if not deadly.
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