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Related FAQs: Moray Eels, Morays 2, Moray Eels 3, Moray Identification, Moray IDs 2, Moray IDs 3, Moray IDs 4, Moray IDs 5, & Moray Selection, Moray Behavior, Moray Compatibility, Moray Compatibility 2, Moray Compatibility 3, Moray Compatibility 4, & Moray Systems, Moray Feeding, Moray Disease, Moray Disease 2, Morays and other Eels & Crypt, Moray Reproduction, Freshwater Moray Eels, Zebra Moray Eels, Snowflake Morays, Other Marine Eels, Conger Eels, Freshwater Moray Eels,

Related Articles: The Hawaiian Dragon Eel Enchelycore pardalis by Marco Lichtenberger,
Moray Eels Bite, But Are They Venomous? by Marco Lichtenberger,
The Zebra Moray (Gymnomuraena zebra), The "Freshwater" Moray Eels, Freshwater Moray Eels by Marco Lichtenberger,

Non-Moray Marine Eels, Snake & Worm Eels by Bob Fenner

The Diversity of Aquatic Life Series

The Moray Eels, Family Muraenidae, pt. 1

To: Part 2

By Bob Fenner

Gymnothorax flavimarginatus

How's that song go? "I'm in the mood for a moray? Well guess what? Me too! Unfortunately, with the exceptions that we'll mention, as a rule moray eels are best left in the seas from which they came. Generally they get too big, are too ornery, even dangerous for aquarists, rendering bacteria-infested bites to the unwary. Of the several varieties often offered to the hobbyist, scads refuse food or readily escape the confines of too-small, inadequately-secured aquaria.

As is the intent of this series I will try to describe this group's spectrum of appealing and undesirable characteristics, encourage the keeping of it's more adaptable species, and offer fair warning of the shortcomings of the rest. Lastly we'll review details on selection and care.

This information is gleaned from scientific and pet fish literature sources and many years first hand experience in the wholesale livestock industry in ornamental aquatics.

The Group:

Morays are true eels (Order Anguilliformes) one of twenty some families, six-hundred plus species; as opposed to all the other so-called "eel-like" groups of fishes (e.g. wolf-eels that are actually blennies, family Anarrhichadidae spiny eels, Mastacembelidae; and many other non-true-eel groups that have many head lengths into body lengths appearance). Morays lack scales, caudal, pelvic and pectoral fins, instead locomoting with long, continuous dorsal and anal fins. Their scary-looking open-mouthedness is related to their possession of small, restricted gill openings without covers; they're breathing! Muraenids sport lateral line pores on their protruding heads, but not on the body. Think about this last characteristic. Makes sense for animals that spend most their time with just their head sticking out of cover.

There are twelve genera with about one hundred twenty described species of morays, about a dozen of which are regularly accessible to the hobby, with half of those being suitable. They're found worldwide in tropical to sub-tropical seas in shallow to moderate depths. According to Gonzales, in Hawaii they are the next most numerous reef animals after the wrasses, family Labridae.

Traits: The Good, The Bad & Definitely The Ugly:

The pro argument for moray eels is easy; there is such a sharp dividing line between "good" species and individuals and not-so-qualified. A suitable moray is extremely interesting behaviorally, adaptable to aquarium conditions, very disease-resistant and readily accepts offered foodstuffs. Lamentably these criteria exclude more than ninety percent of the family.

Size: The smaller morays attain two to three feet in overall length, the largest more than three meters; yes, close to ten feet. The photo of the Gymnothorax javanicus is a seven footer with a girth greater than your thigh and probably topping the scales at more than sixty pounds.

While it is true that they grow slowly, some having been kept in captivity for several decades, these animals require large living quarters. They are not easily "stunted" to the size of their aquarium. Most morays get to be big animals, requiring large tanks and efficient filtration systems. Crowding into a small system will result in escape behavior, otherwise poor adjustment, and fluctuating water quality.

Wound Danger:

As predators morays are opportunistic omnivores, trying to eat most any fish and/or invertebrate slow enough to grab. Their great sense of olfaction is coupled with bad vision. Whereas individuals in the wild and captivity can be quite docile, even playful, some species and individuals are highly dangerous if provoked or excited by food-smell, because of their bite.

Not all types of morays are nocturnal, shy and retiring; the pictured Panamic Green Moray, Gymnothorax castenatus is a less-than celebrated diver-chaser. They are unpredictable, and at times autistic, not distinguishing where food stops and your fingers start.

A few notes here regarding moray bites. Unless they feel threatened most will leave you alone. If grasped out of fear, looking for food or accident, a moray will let you go. No, you won't have to cut off it's head, geesh. The worst reaction is the most common and dangerous; to jerk your hand back in autonomic reaction, cutting yourself further on the recurved teeth and landscape.

The real problem with these bites is secondary infection. Microbes in the water whether associated with the moray's mouth or not may infect you through any break in your skin, from a bite scratch or puncture. Treat all these seriously. 1) Clean 2) Disinfect 3) Cover & 4) Periodically inspect all such wounds. If inflammation, pain persists I'd suggest a medical visit.

Using long plastic gloves dedicated for aquarium use will prevent most scrapes at home and keep hand-borne pollution down.

Should you be so inclined, or you find yourself on a television game show with a similar query, some morays have been involved in ciguatera (fish food) poisoning. If, when, where in doubt, don't eat them. I have, and they are nothing to write home about. Morays apparently become toxic up the food chain via bio-accumulation, ingesting benthic algae-eating herbivores.

If You're Still In the Mood For A Moray:

System Size, Configuration, Lighting...

Big, Bigger, Biggest; as large a system as possible. A minimum of forty gallons for the smallest of morays. Tank shape should obviously feature length and width versus "show" tank shape.

Hiding places? At minimum two pleasing ones large and dark enough to get entirely out of view.

Subdued lighting and darkened sides and backing are a bonus. Morays enjoy a high degree of routine in their environment and will appreciate a regular, timed light regimen.


Vying with starvation for the number cause of moray death is getting out of the tank and drying up. Look at your system from an aquatic Houdini's point of view. Are there any openings large enough to squeeze the animal's head through? It will. From the inside could you push any part of the top off with your hand and arm? It will. Even with the water level lowered morays can and will liberate themselves.


Are all potential meals. even seemingly tough fare like puffers and triggers and otherwise smart, fast-moving basses, etc. may be sucked in, especially at night. Keep to a systematic feeding schedule or listen for thankful burps. They will even eat cleaner wrasses, but seem to leave symbiotic shrimps (Lysmata, Hippolysmata, Periclimenes) alone.

Different species of morays are rarely found together in the wild and do not generally mix well in captivity. Territoriality within species is not heard of either. Provide mucho space, nooks and crannies and carefully observe your charges.

Feeding, Routine:

All morays are carnivorous, some preferring fishes or invertebrates of different types. Are you looking at a piscivore (e.g. Gymnothorax) or invertebrate-eater (e.g. Echidna)? Check their teeth. Crushing molars are for crabs, etc., sharp pointy types for fish eaters.

A moray skull prep. at the Camden Aq. Most Muraenids are piscivores. Some that tend more toward mollusks and crustaceans fare have fewer, more blunt crushing teeth, as shown in the Zebra Moray pic, bottom right.
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The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

New arrivals will most likely have to trained on live foods. The few species endorsed here almost always quickly adjust to a "feeding stick" routine. I advise building and using one made from rigid plastic doweling or tubing. Keep your hands out of the system for pollution and damage's sake.

Regularity is very important to these eels; smaller specimens may be fed twice a week, larger one's do very well with once a week. Try to schedule frequent water changes the day after these feedings. Provide food of appropriate size, morays don't chew. Cut up clams, shrimp, squid et al. will be much less messy swallowed in strips.

Moray eel not eating -- 09/25/07 My moray eel is refusing to eat! <Species? Tank size? Water parameters (Nitrates, nitrites, ammonia)? Other tank inhabitants? How long is your system running? Any changes/losses? What do you feed? I need more information to help you.> I just bought it yesterday and it was feeding and today it's not eating. <Most morays, except the tiniest specimens, should not be fed daily at all. Really large ones can be fed every two weeks without any issues occurring. Overfeeding and resulting liver diseases are far more dangerous.> I'm worried that it will starve to death, because I have heard that they go on food strikes. <It is important to know species, size, tank parameters etc. (see above) to give proper advice. In general, morays can happily get along without food for weeks and some do without apparent reason and without dying.> Please help, because this is the last eel I am allowed to keep and I would not like to see it die. <Don't panic and don't stress the moray. Let it settle in for a few days. See http://www.wetwebmedia.com/FWSubWebIndex/fwmorayart.htm
for some feeding tricks. They should work with marine eels, too. Write back with more information if you need further help. If you are unsure about the ID send a clear picture. Cheers, Marco.


Is unnecessary if you select a healthy, clean specimen and provide a suitable habitat. The usual two to three week quarantine for newcomers is recommended. Stay away from copper compounds and the organophosphate DTHP (masoten, dylox, Dipterex, Neguvon...) containing remedies; these are deadly to true eels. If your specimen(s) seem to be developing a bacterial and/or fungal infection, check water quality, do a massive water change, or remove them to a treatment tank and treat with the antibiotic erythromycin (Maracyn) to reduce overall bacterial levels.

Don't fret too much if your eel goes on a hunger strike. Morays collected in the wild have empty stomachs and can go for long (months) without eating.

Water Quality:

Temperature tolerance is wide, 72-82 degrees F. for tropical species. Specific gravity is better a little high 1.022 to 1.025. For a useful indicator, keep your eye on pH; 8.0 or higher is a good value. For large, heavy fishes with lots of waste, morays can play havoc with metabolite build-up and related degrading water quality. Morays have a highly developed sense of smell; if there is too much organic or metallic matter, they will show it by behavioral and color changes.

Due to large mounts of proteinaceous food being converted a protein skimmer and power filter is a must. Good circulation, filtration and aeration are paramount. That threatening mouth opening portends not vicious demeanor, but a need for a lot of oxygen.

Frequent ten to twenty percent water changes are recommended. Weekly is ideal, maybe the day or two after feeding.

Keep heaters out of harm's way; where the moray will not smack it or get burned.


Spawning has been observed in the wild with pairs swimming a sort of dance, releasing gametes into prevailing currents. Like all true eels morays have a bizarre larval stage (leptocephalus) with ribbon-like, transparent young.


A) Make sure the prospective specimen is eating.

B) Check it's entire body for sores, scrapes, torn infected

fins. If present, leave it.

C) Are the fishes being cared for properly? If not, why? Offer your advice, place a deposit if you've just got to have it, and wait a couple of weeks.


The main thing I want to stress here is to anticipate erratic activity when first introducing a new moray. Often they will swim about, head out of water, maybe searching for a way out. If to their liking your eel will settle on provided cover, keeping fellow fishes at bay. I'd leave lights on low on the tank or in the room for a few days. If you find your eel on the floor do try to re-constitute it by rinsing off and placing it in a quarantine tank and treating as above.


Should be carefully planned and executed. Though morays are tough, they have soft and slimy skin that is easily abraded by rough handling. Netting them almost invariably results in a thrashing specimen on the floor, much frazzled hobbyist nerves and non-sanctioned use of bath towels. Do this instead: Procure a thick (or doubled semi-thick) fish bag(s), roll the edge up, place in a scooped-up fashion in the tank and scoot the moray into the bag underwater. Maybe needless to say, but carefully lift the eel with minimum water from the tank in the bag. Now wasn't that easier? Now let's chat concerning species to look for and one's to avoid.

Some of the Good to Great Captive Species of Morays:

Gymnomuraena zebra, the aptly named Zebra Moray is a slow-moving chocolate black with vertical white striped beauty. (photo). The suitability for aquaria of the species is reflected in longevity records. Our old service company had some in rentals for fifteen years. There are twenty-something year citations.

Genus Echidna:

Echidna catenata (Bloch 1795), the Atlantic "Chain-Link" Moray at about two foot maximum is likewise easy to maintain and peaceful. Feed once a week with cut-up crab, shrimp, krill, squid... may have to be trained or maintained on live crabs, shrimp. Aquarium photo.

The Snowflake, Starry, or Diamond-Backed Moray, Echidna nebulosa (Ahl 1789) is a fabulous aquarium species; small, compatible with other fish species and adaptable to captivity. It is certainly the most peaceful, outgoing and desirable moray species. To about thirty inches total length. Base color of silver gray with black and yellow "snowflakes" randomly sprinkled over the lower body. Aquarium pix.

Echidna polyzona (Richardson 1844), the Banded Moray. Indo-Central Pacific; Red Sea to the Marquesas, Hawaiian Islands. To two feet in length. A crustacean eater. N. Sulawesi photo.

Genus Enchelycore:

Dragon morays, Enchelychore pardalis from Hawaii are striking with white bodies and variegated black, yellow and red markings. Their name derives from the presence of elongate, pointed jaws and long posterior nostril tubes. They command a high price for their beauty and adaptability, and are worth it. Attractive to a lesser degree, but frequently seen in the trade, the Mediterranean Muraena helena reaches the about half the Dragon Moray's length, about two feet. Aquarium photos.

Verticals (Full/Cover Page Sizes Available)
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The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

"Nicer" Gymnothorax:

Gymnothorax favagineus (Bloch & Schneider 1801), the Leopard or Tessellated Moray is one of the few members of the genus I can honestly endorse for home use. Most just get too big and mean (to at least 5.9 feet, possibly closer to ten in the wild). It is a handsome brownish black overall with a network of white to yellow reticulations. G. permistus is a junior synonym of G. favagineus. Shown: a three foot individual in captivity, and a two footer below.

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The Gray Moray, Gymnothorax (Siderea) griseus (Lacepede 1803), is a small (three foot max.) compatible species, though expensive; hailing from the Red Sea and west Indian Ocean. Red Sea photo.

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Golden dwarf moray (G. melatremus Schultz 1963) To 23 cm. Aq. pix.

Summary.php?ID=7284&genusname= Gymnothorax&speciesname=melatremus
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The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Gymnothorax miliaris Kaup 1856, the Golden Tail Moray. Western Atlantic; Florida to the Antilles. To twenty eight inches in length. One of my favorite aquarium members of the family due to its inherent small size, good looks, and good numbers to be found in the wild. A head of one off of Bimini, and a tail for show in Cozumel. Also occurs as a "golden morph", shown below. http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?

Verticals (Full/Cover Page Sizes Available)
Gymnothorax moringa Cuvier 1829, the Spotted Moray Eel. Tropical eastern and western Atlantic coasts. To four feet in length. (most less than half that in captivity and the wild)Common in the wild. Bahamas and St. Thomas pix. An easy-going species for aquarium use.

Verticals (Full/Cover Page Sizes Available)
Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Gymnothorax rueppelliae (McClelland, 1844), the Banded Moray. Indo-Pacific: Red Sea and East Africa, to the Hawaiian, Tuamoto, and Marquesan islands. Feeds on fishes and crustaceans, mainly at night. Wary and often aggressive. Grows to roughly 31 inches (80cm). Bands more prominent in juveniles, fade as the animal gets older. Also distinctive brown spot at the back of the mouth, helps ID this eel. This one hiding in the coral at night, of Kona, Hawai'i.

Gymnothorax (Siderea) thyrsoidea (Richardson 1845), the White-Eyed Moray. Indo-Pacific; Christmas Island to French Polynesia. To twenty six inches in length. Found in shallow water, often with other Moray species. N. Sulawesi images.

Verticals (Full/Cover Page Sizes Available) Linked

Genus Muraena:

Muraena argus Gilbert 1898, the Hour-Glass Moray. Eastern Pacific; Mexico to Peru. To a meter in length. A juvenile in the Galapagos and adults off of Cabo San Lucas, Mexico's Baja tip, and the Galapagos Islands, juveniles second row below.
Verticals (Full/Cover Page Sizes Available)
Muraena clepsydra (Steindachner 1870), the White-Spotted Moray. Eastern Pacific; Mexico to Peru, including the Galapagos. Prominent dark spot with white border over the gill opening. To almost a meter in length. One off of the Galapagos Islands.

Verticals (Full/Cover Page Sizes Available)
Muraena lentiginosa Jenyns 1842, the Jewel Moray. Eastern Pacific; Mexico's Baja to Peru. To about two feet in length. Another delightfully small member of the genus. Below: a one foot juvenile, a near maximum size individual in captivity, and a reticulated/mottled patterned one in the Galapagos.
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Muraena pavonina Richardson 1845, the Whitespot Moray. Western Atlantic: northeastern Brazil and the mid-Atlantic ridge. Eastern Atlantic: Ascension Island. To 51 cm. in length. Aquarium photo. http://fishbase.org/Summary/
speciesSummary.php?ID=27231&genusname=Muraena &speciesname=pavonina

To: part 2

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