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Issue: September 2009

Morays!

Author: Mike Maddox

MADD
Photographer: Mark Smith
Fearsome teeth, large size, and lurking behaviors make moray eels the object of both fascination and fear. A saltwater professional delves into the hidden world of these reef predators and provides advice for their keeping in the home aquarium.

Moray eels are fascinating, beautiful, and universally recognized fish that can make a unique and stunning addition to a marine aquarium. They are tough, disease resistant, hardy, easy to feed, and a few make excellent aquarium fish (some are even reef safe!).

There are many moray eel species. The order Anguilliformes, the true marine eels, comprises nearly 700 species! However, only a handful are suitable for the home aquarium, many of which belong to the genera Gymnothorax or Echidna, though this article will also focus on some species from other genera.

 
Housing Considerations
 

While going into detail about setting up and maintaining a marine aquarium is not possible here, I’d like to touch upon a few important issues to keep in mind when considering a moray eel.

Moray species differ greatly in size, so they are suitable for many different-sized aquariums. It is important to remember that many factors affect proper stocking levels, especially water changes. In any case, all moray eels require aquarium systems that can handle large volumes of waste products. As carnivores, these fish produce large volumes of highly nitrogenous wastes—in other words, lots of ammonia. In addition, most species are large fish, with a correspondingly large biomass, which also means they will produce a lot of waste. An efficient biological filtration system, ample water changes, and a powerful protein skimmer will be absolutely necessary to maintain proper water quality.

 
Tank Size
 

Among the many factors to consider when figuring what size tank you need for a given fish is the size of the animal itself. These factors can be in opposition—heavy-bodied fish, like morays, need larger tanks than slighter animals, but sedentary fish, like morays, need less room than more active animals. A reasonable rule of thumb for a minimal tank size for any species is: a minimum width of more than the length of the fish so it doesn’t have to fold itself in half to turn around, and a length of several times the length of the fish so it can swim a bit before hitting the end.

Now, morays are quite long for their mass (in other words, snake-like) and much more flexible than most other fish; nevertheless, the fish should be able to navigate its home without undue contortions. A 30-inch moray can turn around in an 18-inch space, but it certainly will appreciate having more width. When you factor in their voluminous wastes, you want a good volume of water in a large tank.

While smaller species can make do in a 75-gallon aquarium, larger morays will require a 125-gallon tank or larger. The largest morays, which are not recommended for home setups, require monster tanks like those at a public aquarium.

 
Tank Setup
 

These shy fish require a tank with plenty of caves and other places to hide. Ensure that there are at least two areas in the aquarium large enough to conceal the entire eel. Large rocks elevated on smaller rocks and 4-inch-diameter PVC pipe from your hardware store both make excellent moray eel shelters. An eel without adequate hiding spots will be constantly stressed, so be sure to provide plenty of cover to ensure comfort. An eel that is comfortable in its environment will be less shy, less prone to disease, more willing to eat, and will display more natural behavior.

Be aware that all morays are escape artists. Any opening in the lid of the aquarium large enough for an eel to get its head through will be used to escape. A common cause of death among moray eels is escape and desiccation, so take steps to prevent this and carefully inspect all lids and canopies for moray-sized openings. Tight-fitting lids fastened in a way so the eel cannot push the lids up and off are the only option. It is often difficult for a hobbyist to realize the incredible strength, suppleness, and sliminess of a moray. They can easily push aside an unsecured glass or acrylic cover and slither out of their tank. It takes a complete cover under considerable weight to thwart these animals that are instinctively driven to explore any gap or crevice with their powerful snouts.

 
Feeding
 

All moray eels are carnivorous and consume either fish or crustaceans. Since a constant supply of live silversides and blue crabs is unlikely to be available, you’ll want to train your eel to accept fresh or frozen seafood instead. A feeding tool is a necessity (I use tongs and shish kebab sticks) to avoid injuries from their powerful jaws. Eels have an excellent sense of smell, and after being given a week or so to acclimate to the aquarium environment, they should readily accept strips of shrimp, oyster, crab, crayfish, or frozen marine diets when dangled at the end of a feeding stick.

Morays should not be fed often. Juveniles should be fed twice a week, and eels nearing adult size should be fed once a week or even less. It is much more common for an eel to die from overfeeding and associated internal organ problems than from starvation. Feed a variety of meaty seafood purchased from your grocery store (cut into pieces the size of the eel’s mouth or smaller, as eels do not chew), and soak all foods in a vitamin supplement before feeding to ensure proper nutrition. Never attempt to hand-feed your moray.

 

Moray Safety

 

Be warned that moray eels have poor vision, and when they smell food they may bite at anything, including your hand, which would result in a nasty wound that could easily require medical attention. Always use feeding sticks or tongs, and be extremely careful whenever your hands are in the tank. I don’t mean to imply that morays are nasty. Despite their B-grade movie reputation, moray eels are timid fish, and they don’t attack unless provoked, but they can injure you inadvertently or if you spook them or make them feel threatened.

Although they can and certainly will defend themselves, they do not go out of their way to provoke a fight. They spend the day backed into a hole, with at most their head protruding. At night they emerge to slide along the reef, looking for sleeping prey. Not surprisingly, they rely mostly on a keen sense of smell, not vision, to locate food. Hand-feeding these sharp-toothed, almost blind predators often leads to serious injuries when they unwittingly bite the hand that feeds them. It is not clear whether or not venom is usually involved in moray bites, but severe trauma and infection are certainly likely. The widely circulated online video record of a foolish diver who donates a thumb when teasing and feeding sausages to a moray should suffice as a suitable warning to aquarists keeping these animals.

 

Morays for the Home Aquarium

The following morays make excellent candidates for the home aquarium, being adaptable and easily weaned onto non-living foods. All of the following species should live for a decade or more in captivity, as long as you strive to maintain quality water conditions, prevent escapes, and do not overfeed. Most moray species tend to be territorial; only one moray should be kept per aquarium unless otherwise noted.

 

Snowflake Moray
Echidna nebulosa

Maximum Size: 40 inches

The snowflake moray is the most commonly offered moray in the trade, and for good reason: It is a small, docile, colorful, and hardy moray that is easily kept in the community or reef aquarium. Multiple snowflake eels can be housed in the same aquarium because this species is very docile, even towards its own kind. The snowflake moray will consume crustaceans, so do not house it with ornamental crabs, lobsters, or shrimp. For those wanting to try their hands at keeping a moray, the snowflake moray comes highly recommended.

 

Zebra Moray
Gymnomuraena zebra

Maximum Size: 60 inches

The beautiful zebra moray is a striking eel for the large home aquarium, being docile toward fishes and invertebrates, except for crustaceans. This large eel adapts readily to captivity and has a very unique pattern of alternating black, brown, and white vertical stripes. Ensure that plenty of hiding places are available, as the zebra moray can be very shy, especially during daylight hours. Be aware that this species is a fast grower—my zebra moray is growing almost an inch per month! When choosing a zebra moray, I recommend purchasing a smaller specimen, since it will adapt to aquarium life faster than larger eels.

 

Chain-Link Moray
Echidna catenata

Maximum Size: 65 inches

The chain-link moray has a unique pattern of black or brown on white. It is a peaceful eel, also consuming crustaceans. Similar in size, care, and temperament to the zebra moray, this is another unique species that makes an excellent centerpiece in the large marine aquarium. This is the largest of the morays I recommend for the home aquarium, so be prepared.

 
Golden or Goldentail Moray

Gymnothorax miliaris

Maximum Size: 27 inches

The golden moray is an excellent candidate for a marine aquarium because of its relatively small adult size and docile nature. The golden moray occurs in several color variations, ranging from a bright yellow and gold to a speckled brown and gold. The golden moray will consume crustaceans and possibly small fish, so caution is advised when selecting tankmates. The golden moray, along with the snowflake moray, is an excellent first eel for the less experienced aquarist.

 

Dragon Moray

Enchelycore pardalis

Maximum Size: 36 inches

The dragon moray is a very rare and unusual eel that is aptly named. Sporting a red-, orange-, yellow-, brown-, and white-spotted pattern with red-and-white nostrils that flare vertically and prominent, sharp teeth, this moray appears to be a miniature dragon when gaping at you from a rocky cave. While it is a good choice for larger setups, it is very rare and commands a steep price. The dragon moray is a piscivore that will definitely consume any fish the size of its head or smaller, so select tankmates with caution.

 

Horned or Honeycomb Moray Muraena melanotis

Maximum Size: 40 inches

Somewhat similar in pattern to the dragon moray, the horned moray occurs in a few color variations, from a black-and-white honeycomb pattern to an orange-, brown-, and white-spotted pattern. The honeycomb moray feeds mainly upon crustaceans and is usually safe with all but slow, small fish.

 
Dwarf or Golden Dwarf Moray

Gymnothorax melatremus

Maximum Size: 10 inches

Here’s one more species. People often ask if there isn’t a dwarf moray they can keep in their aquarium that is not big enough for any of these other species. The answer is a cautious “yes, there is.” Cautious because the fish, the golden dwarf moray Gymnothorax melatremus—which reaches a maximum size of less than a foot!—is extremely hard to find and expensive. Expect to pay a minimum of about $400, and perhaps much more, depending on size, condition, and coloration. You could easily buy 10 or more snowflake morays for the price of one of these.

 
Conclusion

While a great many moray eel species are simply too large even to consider keeping, these half dozen or so species will all live long and healthy lives in the home aquarium, provided that their few needs are met adequately. I highly recommend this unique group of fishes to anyone looking for a large and attention-getting fish for their display tank.

 
Resources
FishBase: www.fishbase.org
WetWebMedia: www.wetwebmedia.com D
 
 


See the full article on TFH Digital http://www.tfhdigital.com/tfh/200909/#pg105

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