Over two years have passed since the introduction of Reefkeeping.com, which from the beginning included the regular monthly column "Fish Tales." Recently, I came to realize that neither the guest columnists nor I have done a column on a group of marine fish that is very popular among hobbyists worldwide. With this in mind I decided not only to focus the June column on Blennioids, but to feature this family's most species-rich genus. Although most members of Blenniidae have a rather bland coloration, and have looks described as "a face only a mother could love;" all members have "personality." It is this trait that makes them so popular to aquarists. The fact that Ecsenius species are, however, the most attractive looking group of the family, and the particular genus that I choose to focus on this month, is no coincidence. Without a doubt, the beauty of some Ecsenius species rivals the most attractive marine fish. Without further ado, let's take a look at one genus of the Comb-toothed blennies.

Meet the Family

Photo courtesy of Greg Rothschild.

Blennies have been divided into four families: Blenniidae, Chaenopsidae, Clinidae, and Labrisomidae. The Comb-toothed blennies are from the family Blenniidae, which is the largest of the four families and is rather diverse, consisting of six tribes, 53 genera and roughly 350 species. The vast majority of these blennies lack a swim bladder (although Aspidontus, Meiacanthus, Petroscirtes, and Plagiotremus all have a small swim bladder), which results in the fish lying or resting on coral, rock, substrate, and even the sides of the aquarium. Some members of this family are considered mimics of poisonous fish, while other members are quite poisonous themselves. Finally, all family members lack scales.

The 51 members (see below) are awarded such status only if they have both an anterior and posterior canine tooth. No other members of the tribe Salarini have these specific teeth, although most members of the tribe Parablenniini do. In the case of Ecsenius, the anterior canines are so similar to the incisors that in many cases those teeth cannot be differentiated except by scientific osteological preparations. Finally, the presence of the teeth "indicates that Ecsenius is the sister group of all Salarinni and that it is plesiomorphic for anterior canines" (Springer, 1988).

Additionally, males and many females have elongated upper and/or lower caudal lobes; no other Salariini nor Blenniini possess this feature. Also, Ecsenius lacks circumorbital bones, whereas all other members of Blennidae have four circumorbital bones. Finally, except for a few members of Nemophidinae, only Ecsenius have their lateral extrascapular bones fused with the pterotics.

Although one subgenus was used in the past to help differentiate Ecsenius midas from all other members of the Ecsenius genus, this subgenus, Antiblennini is no longer in use. Springer (1988) recognized the lack of "obvious synamorphy which defined all other species of Ecsenius to the exclusion of Ecsenius midas." As such he felt no less than two additional subgenera would be required to maintain nomenclatural consistency, so until further research was able to form better interrelationships within the genus, the best move was to reconsider his earlier notion of E. midas being a monotypic subgenus and thus Ecsenius currently is not subdivided into subgenera.

In an attempt to organize Ecsenius species into groups that contain species that are somewhat similar, 12 groups have been recognized and the species spilt up accordingly (see below). The Pulcher Group, consisting of three species, all have 13 dorsal fin spines, 14 pectoral fin rays, and 11 precaudal vertebrae. The Stigmatura Group maintains four species which all have a black spot behind the anus. Frontalis is recognized as the lone species in this group, one of three groups with only one member, because they have the highest number of pectoral fin rays at 15. The Yaeyamaensis Group is divided based solely on color patterns that exist on the jaw-line, head, and the base of the pectoral fins. Pink or orange stripes are indicative of the nine species of the Opsifrontalis Group. Pictus and Lineatus, the remaining two groups comprised of only a single species, are recognized as such because of their unique coloration. The four members of Mandibularis all have a high number of canine teeth. Whereas all other species have one or two posterior canines, the Mandibularis members have between four and eight canines. Besides being the smallest members of the genus, the Prooculis Group has a distinctive sexual dimorphism, with dark crescent shapes on the head of males, and pale crescent shapes on the females. Cirri both anterior and posterior to the anterior nostril are what separate the two species of the Bicolor Group from all others, which have cirri only posterior to the anterior nostril. The final group of eight species, Oculus, was at one time recognized as a single species. Like several other groups, these members share a unique color pattern unto themselves - a snow white spot next to the pectoral fin's axil (Springer, 1971; 1976; 1988).

In the Wild

Comb-toothed blennies are located throughout most of the Indo-Pacific region, but do not extend into the eastern Pacific. The overall range of the genus is best defined as the eastern coast of Africa as far east as the Tongan Islands, and from Ryukyu Islands north of Japan to as far south as the southern edge of the Great Barrier Reef. Despite a single report of E. bicolor from Hawaii, no species are currently recognized as present in the Hawaiian Islands. Ecsenius frontalis and E. pulcher can both be found in only the Red Sea and the Persian Gulf, which typifies the localized distribution of species in this genus. In fact, the limited distribution seems to have baffled researchers, as the planktonic stage should support a wider distribution than it currently does. Springer (1988) believes the cause of the limited distribution lies in the tectonic history of the Indo-Pacific region.

If corals are not present, neither are Ecsenius species. The distribution of comb-toothed blennies is correlated directly with areas of dense coral growth. This includes the surge zone, quiet lagoons, and even the tidal pools, provided dense coral growth is plentiful. They are generally found at shallow depths, sometimes as shallow as a couple of feet, but some species may on occasion be found at depths below 120 feet. They are not, however, located along shorelines, even if corals are present. Most individuals have a limited range of motion, rarely moving more than several feet in any direction. These blennies will "hole-up" in small crevices and are virtually impossible to evict from their quarters once they are within it. Under close observation even considerably larger individuals were unable to launch an effective offensive attack against a smaller fish already in a hole. Additionally, these fish are non-violent and will generally retreat into a small crevice if threatened.

Ecsenius species hatch into life at roughly 3.5 mm of total length and by the time they reach 12 mm they are nearly identical to adults in color and morphology. Little else is known about the reproductive habits or impending fry development of this genus. What is well documented, however, is the sexual dimorphism that is present amongst genus members. Although several variations exist, and vary depending on the species, all Ecsenius share the common Blenniid traits of a greatly reduced first dorsal spine for females, as well as a triangular fleshy lobe encompassing the large urogenital opening, while males have a small opening at the end of the small tube. Males are likely to attain a larger adult size than the females. For instance, the largest E. bicolor male collected measured 77 mm, while the largest female was only 59 mm. Further, of individuals measuring more than 24 mm, 40 of 128 males exceeded 55 mm, compared to only two of 110 females. Males develop thick fleshy tips on the ends of their anal rays and have longer caudal fins than equally sized females. Additionally, some species' females (E. bicolor, E. nalolo) have significantly more teeth than males.

The best defense of most members of Ecsenius is limited to "holing up" in small crevices. Certain members of the genus, however, are known to mimic various other fish, which is likely a better defensive mechanism, at least for them. Ecsenius bicolor was once thought to mimic the poisonous fang-toothed blenny Meiacanthus atrodoralis not only in color at depth but also in morphology (Springer, 1971). However, further research by Springer (1988) prompted him to exclude Ecsenius bicolor from mimetic relationships mainly because color variations within the two species were not consistent from one location to the next. Ecsenius gravieri mimics M. nigrolineatus, another fang-toothed blenny. Further mimicry is said to exist between E. midas and the anthiine Anthias squamipinnis. This is, however, loosely based on the fact that E. midas is noted to hover in dense schools of A. squamipinnis. This situation could simply be safety in numbers, rather than mimicry (Springer, 1971).

In the Home Aquarium

Without a doubt, Ecsenius species can do well in home aquaria provided the proper precautions are taken before their introduction into the aquarium. Although many species can be considered perfect reef aquarium fish, other species or even other individuals of "safe" species may begin to nip at clam mantles, LPS polyps, or to scrape SPS tissue. It has been hypothesized that they are capable of utilizing the symbiotic algae that reside within these tissues. Much like dwarf angelfish are "hit-n-miss" for reef aquarium suitability, so are Ecsenius blennies. Be forewarned - it is not easy to remove these small fish once they are in the aquarium. Possibly the best option is removing the entire rock in which the blenny has decided to hide out. Once high and dry they have a tendency to jump clear of the rock. If you are not careful they will land back in your aquarium.

A pair of Ecsenius lividanalis sit side-by-side in the wild. This is one of five species that also has a bi-colored color pattern. Pay close attention to the spelling as this species was scientifically misspelled for nearly 20 years. Photo courtesy of John Randall.

With large individuals stretching the measuring tape to a whole ten centimeters, and with the tendency of these fish not to roam great distances, they make ideal additions to smaller aquariums. A single specimen will generally do well in aquariums of 30 gallons or larger. If you wish to find a male/female pair, be sure to carefully use the characteristics laid out here to discern sexes, and provide, as a minimum, a 75 gallon aquarium for your pair. If two males are added to the same aquarium, it is likely one will perish. Mixing species is not recommended because, once again, they will generally not coexist and the weaker of the two will be eliminated.

Left: A difference in both size and coloration invoked the concern as to whether Ecsenius aequalis was actually two different species. For now, even though individuals from Osprey Reef and the Great Barrier Reef differ (GBR individuals are on average 25% larger), they will continue to share one name. Photo courtesy of John Randall.

Right: Originally collected from the Banda Islands, Ecsenius bandanus has the largest distribution of any Prooculis member, which really isn't saying much as this entire group is geographically limited. Photo courtesy of John Randall.

Although Ecsenius species are not aggressive in the wild, small gobies may be at risk from them if kept in the same aquarium. The risk escalates if this combo is placed into a smaller aquarium. Ecsenius species will defend their small patch of reef, and defenseless gobies will be unable to escape their aggression. Barring large or aggressive predators, Ecsenius can adapt to an aquarium with most other fish. Large but non-predator fish such as surgeonfish, fairy wrasses and angelfish will largely ignore these blennies. As can be assumed for most small fish, placing Ecsenius with Groupers, Scorpionfish, or other predators is unwise and will certainly end with a meal for the predator.

	Left: The Smoothfin Blenny, Ecsenius frontalis, has three distinct color forms. The striped or nigrovittatus form can be seen above, while the frontalis form can be seen below. The bi-color form, also called albicaudatus, is absent from the photos given here, but as the name implies, it has two distinct colors divided in a similiar fashion to E. bicolor. Photo courtesy of Richard Field.
Right: Photo courtesy of Richard Field.

Compatibility chart for Ecsenius species:

Fish	Will Co-Exist	May Co-Exist	Will Not Co-Exist	Notes
Angels, Dwarf	X			Good choice.
Angels, Large	X			Good choice.
Anthias	X			Good choice.
Assessors		X		May be harassed by Ecsenius species.
Basses	X			Good choice.
Batfish	X			Good choice.
Blennies			X	Most blennies will not mix well in a home aquarium.
Boxfish	X			Good choice.
Butterflies	X			Good choice.
Cardinals	X			Good choice.
Catfish		X		Large adults may try to consume Ecsenius species.
Comet	X			Good choice.
Cowfish	X			Good choice.
Damsels	X			Good choice.
Dottybacks	X			Good choice.
Dragonets	X			Good choice.
Drums	X			Good choice.
Eels		X		Large adults may try to consume Ecsenius species.
Filefish	X			Good choice.
Frogfish			X	May consume Ecsenius species.
Goatfish		X		Large adults may try to consume Ecsenius species.
Gobies		X		May be harassed by Ecsenius species.
Grammas	X			Good choice.
Groupers			X	May consume Ecsenius species.
Hamlets	X			Good choice.
Hawkfish	X			Good choice.
Jawfish	X			Good choice.
Lionfish			X	May consume Ecsenius species.
Parrotfish	X			Good choice.
Pineapple Fish	X			Good choice.
Pipefish			X	An aquarium dedicated to Pipefishes is recommended.
Puffers	X			Good choice.
Rabbitfish	X			Good choice.
Sand Perches	X			Good choice.
Scorpionfish			X	May consume Ecsenius species.
Seahorses			X	An aquarium dedicated to Seahorses is recommended.
Snappers			X	May consume Ecsenius species.
Soapfishes			X	May consume Ecsenius species.
Soldierfish		X		Large adults may try to consume Ecsenius species.
Spinecheeks	X			Good choice.
Squirrelfish		X		Large adults may try to consume Ecsenius species.
Surgeonfish	X			Good choice.
Sweetlips			X	May consume Ecsenius species.
Tilefish	X			Good choice.
Toadfish			X	May consume Ecsenius species.
Triggerfish		X		Some species are overly aggressive. Odonus niger may be an exception.
Waspfish		X		Large adults may try to consume Ecsenius species.
Wrasses	X			Good choice.

Note: While many of the fishes listed are good tank mates for Ecsenius species, one should research each fish individually before adding it to the aquarium. Some of the fish listed above are better left in the ocean or for advanced aquarists.

	Left: The picture shown here for Ecsenius pulcher shows one of three distinct colorations. The horizontal striping has on occasion been considered a mood induced coloration because the horizontal stripes fade in lieu of the more traditional vertical bi-colored form when dead. Photo courtesy of Richard Field.
Right: Ecsenius pulcher, showing a traditional bi-colored coloration. Photo courtesy of John Randall.
	Left: Ecsenius pulcher, showing a uniform dark coloration. Photo courtesy of John Randall.
Right: Ecsenius aroni, a resident of the Red Sea and the Gulf of Aqaba, is a deeper dwelling species of Ecsenius, regularly occuring deeper than 100 feet. Photo courtesy of Richard Field.

Even though these comb-toothed blennies are not found in the wild without lush coral gardens around them, they seem to adapt to aquariums without corals without stressing out. This may, in fact, be the best option, as it eliminates the concerns of mantle nibbling and coral polyp feeding. One of the largest concerns, however, is providing adequate hiding spaces. With or without coral, many small crevices and look-outs should be provided. These will be very important, especially upon first introducing the blenny to the aquarium. Once settled in, the fish will possibly spend a majority of its time sitting on ledges or on the sand in plain view.

Photo courtesy of Greg Rothschild.

Once the tankmates and rockwork are under control, the choice of food should be considered. Many of these species are herbivorous with a strict diet of microalgae. If you are choosing a species that relies on algae for a large portion of its diet, preparations should be made to ensure microalgae are readily available for it to consume in the aquarium. One of the best places for this to occur is the back glass. By simply never cleaning the back glass, most aquariums will readily grow film algae. By allowing micro algae to grow on viewable panes of glass the aquarist will get the opportunity to witness the kiss marks these blennies leave on the glass when they scrape or comb the algae from it. Hopefully, as time allows the fish to adjust to aquarium life it will become accustomed to eating algae from pellets, flakes, or dried strips sometimes called "nori." Of course, the larger the selection of algae offered, the healthier the fish will be. Although some blennies may consume large amounts of undesirable hair algae, it is unrealistic to assume that an Ecsenius species will make any kind of dent in a healthy crop. In fact, it is quite possible the individual will not consume any hair algae. A single Ecsenius species, E. midas, is not a strict herbivore and will actually prefer to consume zooplankton. For those individuals, mysid shrimp should be considered along with enriched brine shrimp, flake and pellets, or any food designed for smaller carnivorous fish. These same fish will, however, appreciate the occasional vegetable in their diet, so be sure not to starve them of their veggies entirely.

The namesake of the Prooculis Group, Ecsenius prooculis, has the same vivid eye coloration as E. collettei, but instead of spots, like E. collettei, it has stripes. Photo courtesy of John Randall.

Meet the Species

Photo courtesy of Ramon (MrSandman).

Very few Ecsenius species actually show up in the aquarium trade with regularity. Ecsenius bicolor, the Bicolor blenny, is by far the most common of all members of this genus. Therefore, it should not be surprising that E. bicolor also has one of the largest wild distributions of all Ecsenius. Three color variations are scientifically recognized. The variation most common to aquarists is that of the bicolor, whose head and usually more than half the body is uniformly dark, usually brown, while the rear is pale, usually orange or yellow. Other specimens are noted to be a solid dark color, and yet the least common is a striped version which has the pale color running the length of the bottom side of the fish. Collectors have noted collecting on average two striped specimens, the least common color variety, for every 25 bi-colored individuals. No correlation between sex, maturity, or other social considerations has ever been linked to the color variations. Like the vast majority of the species it will thrive only in an aquarium containing microalgae growth. Although easy to keep, it should be noted this species has been known to consider clam mantles and coral polyps as appetizing options on occasion.

A beautiful species and another that can be easily obtained is the Midas blenny, or Ecsenius midas. This is the only species whose natural distribution is larger than E. bicolor's. In fact, the distribution of E. midas is only slightly smaller than the distribution of the entire genus itself. Obviously, the wide distribution plays a large role in this species' availability in the aquarium trade. The Midas blenny is a planktivore, however, and thus may in some regards be easier to care for. Getting these fish to eat from the water column is usually not difficult, and because they do not scrape algae from the rockwork they are also less likely to annoy sessile invertebrates. Additionally, much to the delight of home aquarists, their planktonic nature dictates the fish will spend a considerable amount of time hovering in the water column. The color of individuals varies greatly depending upon the locality. Individuals may range from bright yellow to orange with any combination thereof. Additionally, some individuals will have thin stripes which may vary from black to blue. They are the largest of all Ecsenius, barely reaching ten centimeters of total length.

Possibly the most sought-after specimen is Ecsenius gravieri, or the Red Sea Mimic Blenny. As the common name implies, and as was discussed earlier, this specimen is a Batesian mimic of the fang blenny Meiacanthus nigrolineatus. Like any other fish from the Red Sea region, when you can find one, be prepared to pay handsomely for it. Unfortunately, their beauty does not inhibit their enjoyment of SPS or clams.

Conclusion

Every aquarist shares a different viewpoint with regard to the fish care term "reef-safe." No matter how you personally define it, however, few Ecsenius species likely fit this definition. Although not all specimens will nip clam mantles or scrape SPS tissue, enough of them will that the warning should be heeded. If you must choose an Ecsenius species to add to a reef aquarium, take a serious look at Ecsenius midas because it is a planktivore, and therefore less likely to develop an affinity for sessile invertebrates. Finally, if you plan to avoid LPS, SPS, and clams in your aquarium, there is a strong possibility that any Ecsenius species will be a model citizen for many years.

References:

DeLoach, N. 1999. Reef Fish Behavior. New World Publications. Jacksonville. pp. 96 - 121.
Lieske, E. and R. Myers, 1994. Collins Pocket Guide. Coral reef fishes. Indo-Pacific & Caribbean including the Red Sea. Haper Collins Publishers, 400 p.

McKinney, J.F. and V.G. Springer, 1976. Four new species of the fish genus Ecsenius with notes on other species of the genus (Blenniidae: Salariini). Smithson. Contrib. Zool. 236:1-27.

Michael, S.W. 1998. Reef Fishes Volume 1. Microcosm. Shelburne. pp. 624.

Michael, S.W. 1999. Marine Fishes: 500 + Essential-To-Know Aquarium Species. Microcosm. Shelburne. pp. 448.

Springer, V.G. 1971 Revision of the fish genus Ecsenius (Blenniidae, Blenniinae, Saliriini). Smithson. Contrib. Zool. 72:1-74.

Springer, V.G. 1988. The Indo-Pacific blenniid fish genus Ecsenius. Smithson. Contrib. Zool. (465):134 p.

Springer, V.G. 2000 Blenniidae (blennies). p. 632-634. In J.E. Randall and K.K.P. Lim (eds.) A checklist of the fishes of the South China Sea. Raffles Bull. Zool. (8):569-667.

Springer, V.G. 2002. Ecsenius niue, new species of blenniid fish, and new distribution records for other species in the Opsifrontalis species group. Zootaxa 72: 1-6.

Starck, W.A. 1969. Ecsenius (Anthiiblennius) midas, a New Subgenus and Species of the Mimic Blenny from the Western Indian Ocean. Notulae Naturae, 419: 1-9.