EELS - Eerie or Interesting ?

Next to sharks, eels have to be the most feared and misunderstood fish. Eels invoke thoughts of terror and wanton destruction. This may be because eels are similar to snakes, which also get little love and sympathy. Or perhaps this is another result of Hollywood's simplistic portrayal of this fascinating group of animals. In either case, the fear is unwarranted and one can successfully and safely keep eels in a home aquarium with a little planning and research.

While many people associate eels with saltwater aquariums, there are also freshwater eels, which means customers on both sides of the hobby can enjoy owning an eel.

Freshwater Eels

Almost all freshwater eels belongs to the fish family called Anguillidae and are in the genus Anguilla. There are 15 to 20 Anguilla species including the American eel (Anguilla rostrata). Many of these ells are important sources of food and are commercially grown on farms, especially in Europe.

Few of the Anguilla species are available in the aquarium hobby, however. Probably the most common freshwater eels in the hobby are from the genus Mastacembelidae which are not true eels but classified as spiny eels.The fire and the tire track eels are well-known members of this family available to hobbyists.

The fire eel (Mastacembelus erythrotaenia) comes from South Asia (Thailand through Indochina). The fire eels dark gray to dull black and has red and yellow horizontal stripes that extend from the head to the tail and look a bit like the fire flames painted on a hot rod. This coloration is how the eel got its common name.

The fire eel can reach a length of almost 40 inches in the wild, but aquarium specimens are usually much shorter but still large. This fish needs a large tank with a 55-gallon minimum tank size. Water should be a neutral pH and around 76 degrees Fahrenheit.

As with most freshwater eels, the fire eel prefers to dig and hide in the aquarium substrate. The tank should have a soft sand bottom substrate and flat to rounded rocks without sharp edges under which the eels can hide. Lava rock is not a good choice for an aquarium containing eels.

The fire eel is nocturnal, but can be trained to come out during the day to feed. In fact, a trait common to most eels, freshwater and saltwater, is that they can be trained to eat right from the aquarist's hand. However, eels have poor eyesight and it is not unusual for them to literally bite the hand that feeds them. This is not an aggressive behavior, but the result of poor aim on the part of the eel. Good choices for feed include beef heart, worms and cut fish and shrimp.

Another common freshwater eel is the tire track eel (Mastacembelus armatus). This eel grows large and, in many cases, is mean and aggressive. The common name comes from the color pattern on the sides of the fish that resembles the track of a fire. But this fish may run over any fish that gets in its way.

Most aquarium specimens start at about 6 to 10 inches, but they quickly double or triple in size. Chances are they will start looking at tankmates as swimming morsels of food rather than neighbors. This fish will need lot of room-an aquarium at least 75 gallons-and large tankmates.

They don't seem particular about water quality other than the normal values for nitrogenous waste, neutral pH and water temperature in the mid 70s Fahrenheit. Feeding is easy as they will eat most anything such as beef heart, bloodworms, insects, frozen food and cut seafood.

Saltwater Eels

Eels for saltwater aquarium come from three families Ophichthidae (worm and snake eels), Heterocongridae (garden and conger eels) and Muraenidae (moray eels).

Even though these eels come from different families, they share similarities. Some of these common traits are size, diet and behavior. Most eels are obtained when small but will quickly reach a size of 24 to 36 inches in an aquarium. They are all carnivores and need a variety of meat in their diet.

The majority want to hide in rock and caves, so the aquarium must be decorated accordingly. Last but not least, they are all excellent escape artists.

Together these basic traits mean that one should only put an eel in a large aquarium (50 gallons or more) that has a good filtration system because these fish need a lot more food than more common, smaller marine fish.

Their foods are also higher in protein than flake feed which means there will be more ammonia production, leading to nitrate buildup in the aquarium. Regular water changes are a must with these fish.

Water quality for saltwater eels is the same for all marine fish, as the ocean's basic water parameters, except temperature, are the same worldwide. These eels are all tropical and need a water temperature in the mid 70s.

Behavior differs among eels even in the same family. A popular eel is the zebra moray eel (Gymnomuraena zebra). The body of this eel is dark brown with white stripes running vertically down the body the entire length of the fish. They grow over 4 feet long, but are peaceful and will not bother tankmates. They are good for community marine aquariums but not reef compatible because they will knock corals over. This eels needs a large tank. It eats chopped fish, squid, mussels, clams and more.

Another popular moray eel is the snowflake eel (Echidna nebulosa). This eel also gets its popular name from the body coloration, which features white spots or splashes on a dark back-ground. The snowflake eel does not get as big as the zebra moray, but reaches about 2 feet in the aquarium, and it is easier to maintain. But it is a little more aggressive than the zebra, and it seems to spend its entire life trying to figure out how to escape from the aquarium.

This eel will eat fish and crustaceans smaller than itself, so the selection of potential tankmates is narrowed compare to the zebra. They need rocks and caves and may only come out at night.

There are smaller eels that can be kept in the aquarium and as a colony such as Hass' garden eel (Taenioconger hassi). These eels bury themselves in the sand, and if several are kept in the large tank, they will space their homes in the sand and all rise out of the holes looking like plant stems in the garden. These eels are difficult to keep, you should have the experience and patience needed to be successful with these species. Eels add a whole new dimension to an aquarium and are worth a try. With a little planning, you can be successful and enjoy these fish.

We hope that this guide was of help to you and your hobby.

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