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Keeping Lionfishes and their Scorpaeniform Kin By Anthony Calfo and Robert Fenner
Overview:
Divers and aquarists alike
quickly recognize the need to approach and handle these fishes with distance
and respect. The etymology of the Order says it all: scorpion-form
(from the Greek "skorpios" and Latin "forma"). While most aquarists cannot
name many more members of this Order than the popular Lionfishes, this is a very
large group of fishes! Once you start looking into them, it just gets
larger and larger. Also known as "Mail-Cheeked Fishes," the Order
Scorpaeniformes includes some 35 families, around 300 genera, and over 1,000
species including venomous and non-venomous members. Species of this Order
occur in fresh, brackish, and marine waters. Marine types live in most
oceans of the world, in most habitats, and over a very wide range of depths.
Due to their generally large sizes, plain or cryptic visage, and low activity,
only a smattering of these families and species make their way into the pet-fish
trade. Still, with strict caution while handling the venomous ones
especially, aquarists willing to accept the unique challenges of feeding,
stocking, and husbandry can keep more than a few members of this Order.
Some are even suitable for beginners if given enough space and live food when
necessary. Husbandry for these fishes usually requires oversized
filtration, large aquaria, above average water quality and frequent water
exchanges.
SELECTION
Features unique to many in this group warrant special attention. As with
other scaleless or small-scaled fishes, Scorpaeniform fishes can be very
sensitive to water quality (elevated ammonia in shipping containers, low
dissolved oxygen, etc.) and contaminants. Metals and medicines in the
water have been historically, although variably, risky here too. Though some
specimens clearly demonstrate no less tolerance for common medications, for
example, than large-scaled fishes, we will advise you to error on the safe side
by using half doses for extended times. You should also avoid
organic dyes and metals altogether, such as Malachite Green or heavy copper.
Copper treatments in central holding systems can be an issue with merchants that
do not house Scorpions and other sensitive fishes separately. To put a
fine point on this concern, we are not saying that metals or organic dyes cannot be used, but suggest that they be applied in small frequent
doses (versus large spikes), dilute if necessary, and always with close
supervision on potentially sensitive fishes like some of the Scorpaeniformes. New
imports are not likely to be any more active than typically lazy,
well-established specimens. They are ambush predators and generally "act
the part." Within this Order, however, the Pteroinae Lionfishes are
somewhat of an exception and will cruise the reef actively, sometimes even by
day, looking for prey rather than lay in wait like most Scorpion-, Stone- and
Rockfishes. Nonetheless, this Order overall really is quite sedate.
This behavior runs right down to their rates of respiration, which are slower
than other reef fishes. For their low activity and intent to remain
inconspicuous, mail-cheeked fishes breathe at a relatively slow rate; their gill
movements are about thirty times per minute (that’s only half of some typical
reef fishes!). Be mindful, however, that candidates are not instead making
very labored or exaggerated gill movements, which can be a distinct sign of
trouble.
Harkening back to concerns with scaleless and small-scaled fishes, we advise you
to examine candidates' bodies and fins carefully. Holes in the fins can
heal easily, but broken spiny rays or sores and discolorations on the body are
cause for not purchasing any animals in that system. Arguably, wounds and
infections on Scorpaeniformes are more susceptible to progressing rapidly than
with other fishes. Some species with elaborate crypsis and ornate fleshy
extensions have a lot of soft tissue and spines easily damaged in shipping
(i.e., leafy appendages, thin webbing between spines, etc.). Superior
water quality in the merchant's display and in your quarantine tank for the
first weeks after import will be crucial to help reduce the risk or spread of
infections and disease.
The
appetite of most new imports should not be very different from what you can
expect once they settle in. Although many will demand live shrimp or small
fishes initially, and may continue to do so indefinitely, it should rarely be
difficult to initiate a feeding response. Unless they’ve recently been
fed, they will show interest in food offerings. Play it safe and don’t buy
fishes that don’t eat. If you really want a specimen that is not feeding,
ask the merchant to hold the fish (a deposit may be necessary and appropriate)
for several more days to a week or more as needed. While larger sedentary
predators do not require daily feedings, small feedings several times weekly are
about right. Do not fool yourself into taking home a non-feeding fish with
the hope and belief that it will be more likely to eat with your improved care
and attention. The additional move so soon after the last (import) could
put it off its feed. In fact, very large, well-fed individuals have been
known to fast for weeks after being disturbed, as with a big décor change or
other traumatic events. Still, take heed of this admonition: only
buy fishes that feed heartily in your dealer's tanks.
CARE It
should go without saying that you should NEVER take your eyes off of these
fishes when your hands are in their aquarium. They can “sneak up” on what
they perceive as a risk and inflict a painful wound in seconds. Distracted
aquarists performing routine functions like scraping algae may drive a sweeping
hand or arm down upon the venomous spines. And frankly, some
Scorpionfishes can be sufficiently irritated or threatened to charge
offensively. The
actual environments of these fishes and their provision in captivity are highly
varied. Many species are sedentary, sitting on rocks or upon the seafloor,
blending in with their personal camouflage of colors or skin flaps with possible
algal and sponge growth settlements. Some sway back and forth (e.g., Leaf
Scorpions, Rhinopias
spp.) to blend in with surging weedy habitats. Others burrow partially or
fully under the sand (e.g. reef Stonefish, Devilfishes) while living on open
flats. The bold Pteroinines (Turkey-, Zebra-, Lionfishes), so popular with
hobbyists and public aquariums alike, stay out and about for much of the day.
But all members of this Order should be provided with a dark area of the tank to
call their own - ideally, a large enough cave that they can get out of the light
entirely if they wish. Scorpaeniformes have crepuscular or nocturnal
tendencies and feeding habits - more about feeding later in this chapter.
For aquarists that take the time to research exactly where their specimen comes
from on the reef, the rewards can be rich in observing not only initial
transformations of color and pattern to exploit their cryptic evolution… but
possibly even the growth of (more) elaborate appendages and extensions, as with
leafy and weedy species. So get thee to a planted refugium! Housing Lionfishes and Kin Some other writers have suggested that it’s “okay” to place these fishes in small volumes of water (20 gallons for small species, 55 for larger ones) due to their sedentary natures, but please don’t do this! After many years of being in the service side of our hobby, I have seen many systems with predatory fishes crash. This is often caused by poor alkaline reserve, and too much “metabolite” (heavy bio-load from heavy predators). You can be assured that, other than good filter design and maintenance, providing extra room is your best guarantee to avoid losses and enjoy fishes that thrive and not just merely survive. The larger space will also (importantly) give you more room to avoid being stung while working in the tank. It seems strange to us to even feel the need to mention these realities, yet we see it time and again, having spent our lives in the hobby and industry of aquatic science. It simply defies explanation, beyond the humane treatment of animals, from a husbandry point of view to condone or recommend the keeping of fishes that have potential growth to an adult size in an aquarium that is only as wide as that potential and not more than two to three times as long. We cannot offer an "inches of fish, per gallon of water" rule of thumb with most any fishes, not the least of which Scorpaeniformes, due to the variety of techniques and schedules of feeding, husbandry, and hardware of various aquarists, etc. What we can tell you is to be generous on the size of display aquariums and provide oversized filtration components for these "heavy load" fishes. Even the very smallest species of Scorpionfish will likely require a minimum aquarium size of 50 gallons (~ 200 liters), and the popular Pterois volitans lionfishes will require very long aquariums (>6 feet/2 meters) for growth, with less risk of stunting or dying prematurely as with smaller tanks (under 75 gallons).
Foods/Feeding/Nutrition Lionfishes and their relatives have surprisingly specialized diets. That is to say, while they are highly predatory and most will snap at anything small enough to ingest (and some things that are not!), their long term health and survival in captivity is crucially dependant on finding or being offering the right kinds of food to satisfy their specific nutritional needs. In addition to fish, shrimp, and crabs, various Scorpaeniformes feed upon jellyfish and medusae, polychaete worms and even each other (cannibalism is not excluded in this Order by any means). One of the easiest ways to determine fishes' dietary needs is to research gut analysis for the target specimen; databases like www.fishbase.org and others, along with specific papers when available, detail the nature of diets for numerous species. Aquarists frequently underestimate the importance of doing this, so we continue to have problems with long term vitality, if not survival, of species kept on unnatural diets. In the case of mail-cheeked fishes, any old meat will not simply "do." Much like humans, just because a fish eats certain foods doesn't mean those foods are necessarily good for them! This sad reality plays out time and again with the Lionfish sub-family and their kin. Many, many Lionfishes meet their death from a categorically inappropriate diet of “feeder” freshwater goldfish or the like, which are expensive, hard to digest, cause for “fatty degeneration” of internal organs, are inconvenient… and, in a word, are “bad” for them. Don’t fall into the trap that your predators “need” feeder goldfish (where would they get these in the wild?) or cannot be trained to take killed prey and prepared foods. Pterois lionfishes and many of their relatives can be trained to even take dried carnivore food sticks or pellets! Make no mistake that neither these nor any such predator specializes in wasting energy to catch the fastest and hardest to capture prey. Please! They seek the young, slow, weak, dying, or otherwise unaware specimens. In captivity, however, most will adapt to killed or prepared foods (mostly thawed frozen meats of marine origin). Above all, freshwater prey items are nutritionally deficient and will lead to the death of your marine predator in time. Merchants and aquarists alike that have let their predatory fishes "train" them into thinking freshwater feeder fishes were good, necessary, or all that would be accepted need not wonder anymore why, after a year or two, the predators begin to suffer strange ailments. These ailments include symptoms like renal/vision failure ("they sense the food in the water, but seem like they cannot see it clearly…snapping short and missing?") , or they appear to be unable to swallow the old familiar prey as if they have a "lump" in their throat (goiter, swollen thyroid). Chalk it up to dietary deficiencies or inadequacies (like thiamin deficiency induced by a staple of feeder goldfish) taking its toll over time. You should be determined to offer a wide variety of thawed fresh-frozen meats, dry, or otherwise prepared foods when possible and gut-loaded live prey if absolutely necessary. Identify if your species favors arthropods (shrimp, crabs, and the like) or fishes, and adjust the given diet accordingly. Food
size is more important with fishes from this group, than with others. What
we have here, by and large, are gulping predators. It is not uncommon in
the wild or aquarium alike for a Scorpionfish to attempt to swallow prey that is
too large and die in the process. Although the advice might seem obvious,
this concern speaks largely to tankmates, if any, in the company of mail-cheeked
fishes. Some gulping predatory fishes are legendary for their ambition
(and often times success) at eating prey nearly as long as themselves!
Hobbyists are often surprised by the things that they hear, see and read about
Scorpionfishes trying to eat – like hermit crabs. Now at first it might not seem
so surprising that these dedicated shrimp and crab eaters would take a hermit
crab. What's amazing is that they will try to eat the whole crab – shell
and all! Ouch! Talk about roughage. There are other fishes as
tankmates that present unique challenges or risks, like those with very spiny
aspects about the head and gills, which can lodge into the mouth of an ambitious
predator, killing both fishes out of fatigue and exhaustion if nothing else, in
an unsuccessful attempt to make or break the "greeting." In the confines
of an aquarium, tragedies like this should never happen when aquarists are
mindfully conservative about the things that go into the tank (food and
tankmates). Small frequent feedings (2-4 times weekly or very tiny amounts
daily) and very large, non-threatening tankmates are in order. Popular
staples include thawed fresh-frozen krill (freeze-dried will be accepted too by
some), raw and whole cocktail shrimp (as in, shell-on and not gutted, but cut in
pieces if necessary), various marine fish meats, live grass shrimp or crayfish,
and even live earthworms for the occasional treat for dedicated polychaete
feeders.
COMPATIBILITY For
all of the talk and warnings about Scorpionfish being “big-gulpers” that can
swallow surprisingly larger fishes, they are remarkably vulnerable to some very
common and seemingly non-threatening reef favorites. It's still true, of
course, that they should not be trusted with anything smaller than their
(over-stretched) mouths can handle. To be conservative, make sure all
tankmates are at least twice as long as the Scorpaeniform in residence.
Lionfish in particular may sting their tankmates with their long spines in the
inevitably crowded confines of an aquarium. Victimized fishes may swim or
become spooked into the waiting spines of a Lionfish or the envenomation can
occur by attack under threatening circumstances. Erratic swimming, twitching,
and sudden death will usually occur within thirty minutes of an effective sting.
But most mail-cheeked fish species are more likely to get picked on by other
fish tankmates than vice versa. Turn about, as the saying goes, is fair play,
and despite their spiny and venomous natures, Scorpionfishes do have their
predators. Of the threatening types that they’re likely to encounter in
the wild, these include Sharks, Groupers, Frogfishes, and Moray Eels.
Perhaps more commonly, however, in captivity are prolonged, harassing attacks by
"nippy" fishes like large Angelfishes, Butterflies, Triggers, and Pufferfishes. There are also instances of intraspecific aggression in these fishes, often with apparent males facing off, directing venomous dorsal spines and stabbing each other. These cases are uncommon, but require the separation of individuals if observed. It's not hard to make a case for keeping most Scorpionfishes with few if any other tankmates. While Lionfishes are somewhat of an exception and can make tolerant if not agreeable tankmates for large community fish aquariums, the most popular species used in the hobby, Pterois volitans, simply gets too large for most home-sized aquariums with a number of other fishes. And so, while their needs and husbandry may be underestimated or understated at times… their beauty never is. Part II will examine the various species commonly encountered in the aquarium trade along with eye-popping photos. Don't miss the next issue of Conscientious Aquarist!
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