Scorpionfish: Masters of Camouflage


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.

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.

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.

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.

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:

Fish

Will Co-Exist

May Co-Exist

Will Not Co-Exist

Notes

Angels, Dwarf

 

 
X

Will be consumed.

Angels, Large

 

 
X

Will be consumed. Large individuals may harass Scorpions.

Anthias

 
 

X

Will be consumed.

Assessors

 
 

X

Will be consumed.

Basses

 

X
 

Assuming it is larger than the Scorpionfish, it may co-exist.

Batfish

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Blennies

 
 

X

Will be consumed.

Boxfishes

 
X

 

Large individuals may harass Scorpions.

Butterflies

 

 
X

Will be consumed. Large individuals may harass Scorpions.

Cardinals

 
 

X

Will be consumed.

Catfish

 

X
 

Will be consumed. Large individuals may harass Scorpions.

Comet

 

 

X

Will be consumed.

Cowfish

 
 

X

Will be consumed. Large individuals may harass Scorpions.

Damsels

 

 

 X

Will be consumed.

Dottybacks

 

 
 X

Will be consumed.

Dragonets

 

 

X

Will be consumed.

Drums

 
 

X

Will be consumed.

Eels

X

 
 

Assuming it is larger than the Scorpionfish, it may co-exist.

Filefish

 
 

X

Will be consumed. Large individuals may harass Scorpions.

Frogfish

 
 

X

Will be consumed or may consume the Scorpionfish.

Goatfish

 
 

X

Will be consumed.

Gobies

 
 

X

Will be consumed.

Grammas

 

 

X

Will be consumed.

Groupers

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Hamlets

 

 

X

Will be consumed.

Hawkfish

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Jawfish

 

 

X

Will be consumed.

Lionfish

X

 
 

Will co-exist provided they are unable to swallow each other.

Parrotfish

 

 
 X

Will be consumed. Large individuals may harass Scorpions.

Pineapple Fish

 

 

X

Will be consumed.

Pipefish

 
 

X

Will be consumed.

Puffers

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Rabbitfish

 

 
X

Will be consumed. Large individuals may harass Scorpions.

Sand Perches

 
 

X

Will be consumed.

Scorpionfish

 
X
 

Species dependant. Only try to mix equal-sized specimens.

Seahorses

 
 

X

Will be consumed.

Snappers

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Soapfishes

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Soldierfish

 

 

X

Will be consumed.

Spinecheeks

 
 

X

Will be consumed.

Squirrelfish

 

 

X

Assuming it is larger than the Scorpionfish, it may co-exist.

Surgeonfish

 

 
X

Will be consumed. Large individuals may harass Scorpions.

Sweetlips

 

X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Tilefish

 

 
X

Will be consumed.

Toadfish

 
 

X

Will be consumed or may consume the Scorpionfish.

Triggerfish

 

 

X

Will be consumed. Large individuals may harass Scorpions.

Waspfish

 
X

 

Assuming it is larger than the Scorpionfish, it may co-exist.

Wrasses

 

 

X

Will be consumed. Large individuals may harass Scorpions.

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.

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.

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.

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.

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.



If you have any questions about this article, please visit my author forum on Reef Central.

References:

Burgess, W.E., et al. 1991. Dr. Burgess's Mini-Atlas of Marine Aquarium Fishes Mini Edition. T.F.H. Publications. Neptune City. pp. 114 - 122.

Eschmeyer, W.N., 1969. A systematic review of the scorpionfishes of the Atlantic Ocean (Pisces, Scorpaenidae). Occ. Pap. Calif. Acad. Sci.

Lieske, E. and Myers, R. 1996. Coral Reef Fishes. Princeton University Press. Princeton. pp. 17 - 19.

Michael, S.W. 1998. Reef Fishes Volume 1. Microcosm. Shelburne. pp. 453 - 489.

Michael, S.W. 1999. Marine Fishes: 500 + Essential-To-Know Aquarium Species. Microcosm. Shelburne. pp. 63 - 69.

On the Web:

California Academy of Sciences

Coral Realm
Fishbase



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