That Fish Blog – Aquarium Advice and Information

Classification

More than 200 species of moray eels, all classified within the Family Muraenidae, have been described.  Like the familiar American eel, morays are considered to be true eels of the Order Anguilliformes.  The Superorder to which all eels belong, Elapomorpha, contains over 800 species, including the decidedly “un-eel like” tarpon.

Natural History

Although usually associated with tropical and subtropical habitats, a number occur in temperate seas, and several enter brackish and fresh water on occasion.  Ranging in size from the red-faced eel (Monopenchelys acuta), which reaches only 8 inches in length, to the 12.5 foot long giant green moray (Strophidon sathete), all share a similar body pattern and habits.  The latterly flattened body allows them access to the narrow caves and crevices that form their home base.  Many spend their entire lives within close proximity to a favored shelter, leaving only to mate and foraging nearby.

Some Interesting Facts

Morays can reach quite high densities in suitable habitats, accounting for nearly 50% of the carnivore biomass on some reefs off Hawaii.  Although nowhere considered a delicacy, moray eels are eaten on occasion, and instances of fatal poisoning (ciguatera) have been reported in the Philippines.  A number have unusual life histories…the leaf-nosed moray (Rhinomuraena quaesita) begins life as a dark blue-and-yellow colored male and later transforms into a black-and-yellow female.

Diet and Feeding

Moray eels are carnivorous, and in captivity will readily accept frozen silversides , sand eels , clams  and other fish, crustaceans and mollusks.  Local seafood markets are wonderful shopping grounds for the moray owner – be sure to try mussels, conch and various marine fishes.

Well-fed eels will coexist with smaller fish, but there is always the possibility of predation.  On the other hand, morays are not quick feeders, and indeed can be rather shy about this, so one must take care that they are getting enough food if they are housed with large, aggressive fishes.

Cautions

Moray eels are, like all their relatives, master escape artists.  If this occurs, be sure to move the animal back and forth in the aquarium once it is replaced, so that water is forced through the gills, and treat it with Stress Coat Marine to help replace the skin’s slime coat.

Even small morays are equipped with needle-sharp teeth, and they are not shy about using them in defense or if they mistake your finger for a tasty food item.  The resulting wound almost always becomes infected, and large animals can cause permanent damage.  These are definitely not fish for homes with children.

Longevity

Well cared for specimens can reach impressive ages in captivity.  A huge green moray I worked with at the Staten Island Zoo is still going strong at age 30+.

Snowflake Moray, Echidna nebulosa

Brilliantly patterned in black and white, this Indo-Pacific native averages 24 (rarely to 40) inches in length and makes an ideal first choice for one new to keeping moray eels.  Many individuals become quite tame, reaching out from their lairs to accept food offered on feeding tongs.

They are, like other members of their family, slow feeders, and so are best individually-fed if kept in a community aquarium.  Snowflakes readily accept all manner of frozen or fresh marine foods such as shrimp, clams and fish.  Like all morays, they will not thrive unless provided with a secure retreat.

Other Commonly-Available Moray Eels

The girdled moray (Echidna polyzona) hails from the Red Sea and Indo-Pacific and its small size (to 35 inches) suits it well as an aquarium subject.  It has a relatively small head ….food item size should be adjusted accordingly.

The attractively patterned reticulated or leopard moray (Gymnothorax tesselatus) also appears in the pet trade.  Pale reticulations on a dark background lend it a spectacular appearance, but it reaches 5 feet in length and is therefore suited only to large, very well-secured tanks.

Please write in with your comments and questions.  Thanks, until next time, Frank Indiviglio.

You can learn more about moray eels at:

http://www.fishbase.com/Summary/FamilySummary.cfm?ID=56&CFID=17425107&CFTOKEN=61585937