Some Like 'em Big: The Genus Plectropomus by Henry C. Schultz III

The majority of my past columns have focused upon fish which generally can be considered acceptable choices for reef aquariums, albeit sometimes requiring larger aquariums than others. Such is not the case with this month's column. I decided to change gears slightly and discuss a genus which often is imported with tiny juveniles, but which unfortunately can grow into enormous adults. Along the way they have a tendency to swallow most anything they can, and if fed properly, they have the ability to grow to staggering proportions in seemingly no time at all. Given proper consideration prior to purchase, however, they can make an attractive impact on large show-fish aquariums. Groupers of the genus Plectropomus, known within the hobby as Coral Groupers, are the feature for March's edition of Fish Tales.

Plectropomus, the focal point for this month, is a member of the family Serranidae, often called the Sea Bass family among the non-scientific community. Besides containing Groupers, the Serranidae family boasts Soapfishes and Cave Basses as other popular aquarium genera. More recently, Anthias, which previously was believed to warrant a separate family named Anthiidae, has been reassigned as the subfamily Anthiinae under Serranidae.

Serranidae, in a state of continual reform by ichthyologists, once consisted of only two subfamilies but now is further divided into five subfamilies. In addition to the extremely aquarium-popular Anthiinae, the remaining four subfamilies are Epinephelinae, Grammistinae, Liopropomatinse and Serraninae. Epinephelinae, which contains this month's featured genus, is further divided into five tribes (Allen, et al, 2003).

Besides Plectropomus, an additional 13 genera are classified in the tribe Epinephelini, which encompasses over 160 species. Distinguishing themselves from other Epinephelini, Plectropomus all maintain a consistent dorsal-fin formula (referred to as "VIII, 11" by ichthyologists) in addition to three antrorse spines on their preopercle's lower margin (Randall and Hoese, 1986). A total of seven distinct species are currently recognized within Plectropomus. Of these seven species, six exhibit "a color pattern of small blue spots on the head, body, and median fins (which) become more numerous and relatively smaller with growth." Additionally, "individuals taken from moderately deep water (about 30m or more) tend to be red" (Randall and Hoese, 1986). Finally, one subspecies has been formally described and their distinction is based solely upon color differences.

Regular readers of this column are well aware of the difficulty ichthyologists encounter when trying to categorize genera. Plectropomus' most recent revision includes this passage, which I feel does a more than an adequate job of summing up the research: "Few groups of fishes have been more confused in the systematic literature than the genus Plectropomus" (Randall and Hoese, 1986). As it is, Plectropomus' first five species that were described, including one by Bloch (1790) and four by Lacepede (1801, 1802), were placed into errant genera. Cuvier (1816) recognized their similarities and grouped the fish together, but he failed to assign a Latin designation to them, instead leaving them grouped as "Les Plectropomes." Plectropomus finally became a valid genus after Oken (1817) reviewed Cuvier's work and appointed them with the Latin name Plectropomus.

All this doesn't sound too confusing yet, does it? Well, Quoy and Gaimard (1824), likely oblivious to Oken's work, offered the name Plectropoma in honor of Cuvier. Cuvier, who was apparently proud of Plectropoma, moved three species into this genus and named an additional 10 new species of the genus - none of which is a current member of Plectropomus. Various authors, including Ruppel (1830) and Bleeker (1849), continued to use Plectropoma while continuing to add newly described species.

In an attempt to bring some organization to the genus, Gunther (1859) revised Plectropoma and listed a total of 27 species in it. Unfortunately, as the systematic literature stands today, he included species from eight different genera into his Plectropoma revision. Boulenger (1895) brought Gunther's errors into the limelight when he claimed only two species of Plectropoma in his revision. Since Boulenger (1895) recorded his two specimens, albeit with an errant generic designation, it has been a gradual progression in the proper direction to the point where we stand today. The genus began its progression toward the proper classification when Jordan (1917) ended the confusion between Plectropomus and Plectropoma. Fowler and Bean (1930) reported four specimens; Randall (1973) reported a fifth species; Hoese, et al (1981) added a sixth unnamed species. Finally, as the above listing indicates, we now have Randall and Hoese (1986) to thank for their current classification.

Coral groupers populate the Pacific Ocean's warm tropical waters. None of the seven species is terribly limited, geographically speaking. In fact, most species are fairly widespread and are not in short supply on the reefs where they are located. Plectropomus pessuliferus is perhaps the most limited of the bunch with its one subspecies, P. pessuliferus marisrubri, found only in the Red Sea, although it has been very populous there - so much so that it was such an important food fish, regarded by some as the most popular food fish (Schmid and Vine, 1985), that its numbers are now considered threatened by overfishing. The other subspecies, P. pessuliferus pessuliferus, is the exception in the genus as it is fairly limited geographically. Additionally, even where it has been found it is considered a rarity, found only along Africa's east coast near Zanzibar (originally described specimen), the Maldives (photographed only around 75 feet deep), Sri Lanka (one specimen taken in trawl), Sumatra (one specimen taken in trawl at 130 feet), Fiji (one specimen caught on hook and line over 450 feet deep) and St. Brandon's Shoal (three specimens). Of interest is that all these locations excepting Fiji are in the Indian Ocean. Fiji is, of course, located in the South Pacific. Given that the Fijian specimen was collected from a depth of 450 feet, it is quite likely that this species will be regarded as more popular than collections currently indicate once further deep water research is conducted. On the flipside is Plectropomus laevis. This species populates much of the Indian, South Pacific and North Pacific Oceans. Likewise, Plectropomus areolatus can be found in many of the same waters as Plectropomus laevis, but the former also occupies the Red Sea.

As mentioned above, Plectropomus pessuliferus is an important food fish in the Red Sea. It is not alone, however, as the entire genus is well-regarded throughout the Indo-Pacific as a worthy fillet. In Queensland alone the genus Plectropomus has an estimated annual value of $10 million Australian and $20 Australian/kilogram retail for its fillets. Given the demand for fresh filets from these fish, it is rather interesting to note that Plectropomus species are among the highest carriers for Ciguatera poisoning.

As the reader may have gleaned from the above information, this genus' depth range is widely variable. In fact, depth variances even within a single species are also highly variable. Plectropomus areolatus can be located in water barely deep enough to cover its entire body, yet also can be found to nearly 100 feet. This is perhaps the genus' least variance in depth, whereas the greatest variance would be found with P. pessuliferus, which has been recorded from 30 feet to 480 feet. Regardless of the depth, these Coral Groupers relate almost exclusively to reef walls and steep drop-offs. Caves or holes in the wall are utilized as bolt holes when frightened, but otherwise the fish remains in the open, most often trying to passively mingle with other shoals of fish.

This passive mingling is nothing but an act. More accurately, this passive persona is an integral part of their hunting tactics. As the Coral Grouper gains the other fishes' acceptance, their guard drops. Little by little the prey begins not only to accept, but eventually to ignore, the predator. The end result should be obvious - more often than not the predator is victorious.

Prey can consist of anything that fits into their mouth. Because Coral Groupers can reach over 24" in length, with a mouth designed to engulf large catches whole, this leaves them quite a sizeable menu to choose from. Their preferred food item is other fish. In fact, in a sampling of 468 Plectropomus leopadus that were caught and analyzed, over 95% of their diet was determined to be other fish. Roughly 25% of their diet was fish from the Pomacentridae family, followed closely by Labridae at 20%. It is not picky about the types of fish it eats - anything too slow is inevitably added to their dinner plate. A total of 22 families were identified in these stomach contents (St. John, et al, 2000). Rather surprisingly, two of the fish identified were from the Scorpaenidae and Siganidae families. I say "surprisingly" because those families' members are armored with poisonous dorsal fins. Fish that have been retrieved from Plectropomus species' gut include fish most often associated with sand bottoms such as cardinalfish, all sorts of wrasses and parrotfish, lizardfish, sand perches, gobies, goatfishes, etc. Even finds of pelagic fish such as herring and smelt have been reported. Coral Groupers are even among the few fish which have no qualms about consuming the occasional cleaner wrasse of the genus Labroides (Michael, 2004). In addition to their preference for other fish, Coral Groupers also consume squid, shrimp and other motile invertebrates. More or less, if it moves and the grouper is hungry, it will be eaten.

Spawning has been well documented thanks to both Plectropomus pessilerifus and the Red Sea's fishermen. The fishermen report that in late May these fish gather into large schools on shallow offshore reefs where spawning commences. This is, however, the only time any Plectropomus species gather into schools. Otherwise, these fish live singly as adults except during spawning season, which results in all species other than Plectropomus pessilerifus pairing up in male-female pairs. Goeden (1978) spent an extended period studying the biology of P. leopardus. The end result was that he found P. leopardus to be a protogynous hermaphrodite whose females begin sexual activity at approximately 200mm in total length, followed by their change to a functional male anywhere after 200mm in total length. It is presumed that the rest of the Plectropomus species are also protogynous hermaphrodites.

Like most groupers, Coral Groupers are exceptionally hardy in the home or public aquarium, but there is one caveat: they grow very large. Okay, so maybe there are two caveats - Coral Groupers also have a tendency to consume their tankmates. Despite being easy to care for and generally disease resistant, certain precautions must be taken to in order to ensure their success.

The aquarium's size may be the largest concern of all, and in more ways than one. We are, after all, talking about fish which can reach 24 - 42" of total length. It should be obvious that no normal home aquarium is suitable to hold a fish of such impressive size. Instead, a large non-reef show-fish aquarium will certainly be required. For the majority of Plectropomus species an eight foot long aquarium would begin to approach their realm of reality, but for the largest Coral Groupers it would merely be a good starting point. The family's giant, P. laevis, is perhaps best left to public aquariums, as a grouper nearly four feet long doesn't always make the best house pet. Unfortunately, this also happens to be a very regularly imported species. The hobby's unsuspecting neophytes do not really know what they are in for when they purchase this species' 4-6" juvenile.

Perhaps the newly purchased grouper's exact future proportions remain a mystery to the neophyte, but one thing surely is no longer a mystery once it's in the aquarium - much like a college freshman after last call, Coral Groupers have an insatiable appetite. As this fish continues to grow, its appetite may start to become a concern for some hobbyists, as it will likely become a financial burden. The cost of setting up a 1000-gallon show aquarium will pale in comparison to the lifetime food costs needed to raise and maintain a Coral Grouper. Food items for juveniles include anything prepared for the marine carnivore: squid, silversides, et cetera. As the fish grows, however, it will quickly reach proportions that make feeding aquarium-sized prepared foods unproductive and exceptionally costly. Those hobbyists who live along the coasts will have an easier time than their landlocked colleagues by acquiring foods at bait shops in both the live and frozen variety, or possibly even by net or pole fishing, but the majority of us will likely have to resolve ourselves to our local grocer's seafood freezer. Locate the warm water, saltwater variety of seafood, paying careful attention to ensure you don't accidentally feed your prized grouper seafood prepared with Cajun or Blackened (or any flavored) seasoning. With a small bit of patience and training the grouper will begin to eat most anything dropped into the aquarium. Obviously, this can be both good and bad!

Due to the large quantities of food that will be offered, and thus the large quantity of waste the fish creates, reef aquariums are not ideal homes for Coral Groupers. It is difficult to maintain the pristine water quality so cherished by corals. Instead, the best filtration to consider is the old stand-by: a wet/dry filter. Their ability to process enormous amounts of waste in short periods of time still merits their employment for large show-fish aquariums.

Suitable tankmates for Coral Groupers is a difficult, or should I say, simple, topic to address. Because the grouper will attempt to swallow most anything that moves or smells like food (and eventually anything dropped into the tank), problems arise which are not normally encountered in the traditional home aquarium. Common sense will hopefully kick in here and dictate that anything half the grouper's size or smaller will become food. Therefore, as a juvenile, the list of available tankmates is much larger than it will be in 12 - 24 months as the grouper's size increases. This is important because as the fish grows, you will need to be prepared to remove anything of edible proportions long before its remains can reach your deep sand bed's detritivores. In the compatibility list below you should note that not one group makes the "Will Co-Exist" list. This list is a generalization, however, and some rational judgment is required from the hobbyist. As the list is presented, it takes the fish's adult size into consideration. Because some Plectropomus species can attain sizes of nearly four feet, even a 12" Surgeonfish is not safe. One of the genus' smaller members, however, at only 18 or 20" would likely be unable to swallow that same 12" Surgeonfish. I may have said this already a dozen times, but it bears repeating one more time: Coral Groupers will try to swallow anything that is slower than they are!

Compatibility chart for Plectropomus species:

Fish	Will Co-Exist	May Co-Exist	Will Not Co-Exist	Notes
Angels, Dwarf			X	Will be consumed by Plectropomus species.
Angels, Large		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Anthias			X	Will be consumed by Plectropomus species.
Assessors			X	Will be consumed by Plectropomus species.
Basses			X	Will be consumed by Plectropomus species.
Batfish			X	Will be consumed by Plectropomus species.
Blennies			X	Will be consumed by Plectropomus species.
Boxfishes		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Butterflies		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Cardinals			X	Will be consumed by Plectropomus species.
Catfish			X	Will be consumed by Plectropomus species.
Comet			X	Will be consumed by Plectropomus species.
Cowfish			X	Will be consumed by Plectropomus species.
Damsels			X	Will be consumed by Plectropomus species.
Dottybacks			X	Will be consumed by Plectropomus species.
Dragonets			X	Will be consumed by Plectropomus species.
Drums		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Eels		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Filefish			X	Will be consumed by Plectropomus species.
Frogfish			X	Will be consumed by Plectropomus species.
Goatfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Gobies			X	Will be consumed by Plectropomus species.
Grammas			X	Will be consumed by Plectropomus species.
Groupers		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Hamlets			X	Will be consumed by Plectropomus species.
Hawkfish			X	Will be consumed by Plectropomus species.
Jawfish			X	Will be consumed by Plectropomus species.
Lionfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Parrotfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Pineapple Fish			X	Will be consumed by Plectropomus species.
Pipefish			X	Will be consumed by Plectropomus species.
Puffers		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Rabbitfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Sand Perches			X	Will be consumed by Plectropomus species.
Scorpionfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Seahorses			X	Will be consumed by Plectropomus species.
Snappers		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Soapfishes			X	Will be consumed by Plectropomus species.
Soldierfish			X	Will be consumed by Plectropomus species.
Spinecheeks			X	Will be consumed by Plectropomus species.
Squirrelfish			X	Will be consumed by Plectropomus species.
Surgeonfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Sweetlips		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Tilefish			X	Will be consumed by Plectropomus species.
Toadfish			X	Will be consumed by Plectropomus species.
Triggerfish		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.
Waspfish			X	Will be consumed by Plectropomus species.
Wrasses		X		Large adult individuals can be successfully mixed until the Coral Grouper outgrows its tankmate.

Note: While many of the fish are listed as possible tankmates for Plectropomus species, you should research each fish individually before adding it to your aquarium. Some of the mentioned fish are better left in the ocean or for advanced aquarists.

Of course, it bears mention that Coral Groupers are not your normal aquarium fish, while the vast majority of the fishes presented in the list above are, in fact, regularly encountered aquarium fish. This column has been composed mostly to toss out warning signs to unsuspecting newbies who were duped into buying a juvenile, but I have to consider that some people do have the resources necessary to care for these fish. In that instance sharks and rays would likely make superb tankmates, provided the aquarium's size and filtration were adequate for all the tank's residents.

The aquarium décor's design is vital. The Coral Grouper requires two distinct biotopes in the same aquarium to truly feel comfortable. First, it requires a reef wall which it can dive into and sleep behind. This means that it requires an opening large enough for the fish not only to fit through, but to have the ability to bolt into when frightened. Additionally, the area behind the wall must be large enough to house the grouper with enough space for it to turn around. The option of mostly, if not entirely, obstructing this area from lighting would be ideal. The second biotope will be a large, open sand area. A rock scattered here or there, or possibly even a single pillar, is okay; remember, however, that your goal is to provide open swimming area so the more rock added, the further from that objective you move.

The least common Plectropomus in the wild (minus the sub-species P. pessuliferus pessuliferus) is P. oligacanthus, but this does not necessarily mean that this species is uncommon in the aquarium trade. Like all the other Coral Groupers, this fish often appears as an adorable juvenile in local stores. The very distinguishable elevated anterior soft portions of its dorsal and anal fins have elicited the common name by which it is referred to in the aquarium trade - Highfin Coral Grouper. These elevated portions of the fin are unique to the Highfin Grouper, thereby making it the most easily identifiable Plectropomus species. At barely 24" of adult length, it remains one of the smaller Coral Groupers.

A highly attractive member of the genus is the Leopard Coral Grouper, or Plectropomus leopardus for the ichthyologist types. At just over two feet in length it is another smaller member of the genus, although the term smaller is not exactly descriptive in this instance. Due to the vast territory to which this species is indigenous, it appears in the aquarium trade only occasionally. Unlike many groupers which kick into predator mode once the sun sets, Choat (1968) observed this species comfortably asleep during the night hours. Extensive studies of P. leopardus' home range effectively put the size of our home aquariums into perspective. Although the exact size varied with no correlation to the fish's age or size, a mean home range fell into the 10,000 to 18,000 m2 range. Additionally, the average Leopard Grouper swam roughly 630' per day while one specimen, who apparently was trying to fit into a bikini, swam over 3,600' per day (Michael, 2004). That is a lot of laps around a 10' long aquarium.

The most popular species imported into the United States is Plectropomus laevis. The Black Saddle Grouper, as it is more commonly called, is one of the genus' larger members, attaining lengths of over 40". Its two distinct color phases kept ichthyologists guessing for nearly two centuries. One author (Gunther, 1867) even named this species as having a total of seven distinct species! This species usually cruises outer reef areas several feet off the sand bottom.

If big is your thing, look no further; Coral Groupers definitely fit your criteria. Preparation is key, however, when attempting to tackle a fish that becomes as large as Plectropomus species do. An enormous aquarium with a food budget to match are the two most important considerations, but your work doesn't stop there. Careful consideration must also be given to fellow tankmates if you expect not to feed your other decorative fish to your grouper.

Now, if you purchased one of these fish upon your local store's recommendation, this column should have shed some light onto your impulse purchase, not to mention your local store's intentions and knowledge, or both. At this point you need to honestly consider your ability to provide for this fish long-term. For the vast majority of hobbyists this means finding other housing arrangements for this fish in the nearly immediate future.