EELS! EELS! EELS! EELS!

By Jim Wolf MS. Marine Biology
ODYSSEA ( MASLA ) Volume 5, Issue 1

Eels hold a very distinct position in the fish world. There are many families of eel like fishes, however true eels have a few unique features.

As juvenile fish most are clear as glass and float upon the open ocean and are called Elvers. They then settle out and take up a adult life style.

Eels are all predators that enjoy whole shrimp, clams, or fish about twice a week.  Most eels are very communal, only bothering things they perceive as being food. A well sealed aquarium lid is a must, because these animals are very good at escaping.

Their sense of vision is poorly developed in these animals, but they have excellent sense of smell. A spacious aquarium is compassionate, but they can be confined to very small aquariums with little ill effects. A small cave made of rocks,a low light environment, strong mechanical filtration and no aggresive tankmates make for happy eels.

Despite the huge numbers of eel species there are only two families of  eels seen in the hobby.

Conger eels of the family Anguillidae are true eels, and are extremely hardy.  The dominant Eel family is Muraenidae, which includes the familiar Moray Eels. There are about 100 species, and 6 genera make their way into the hobby.

Gymnothorax - This along with the genera Muraena and Echidna make up the fish recognized as the Moray Eels. There are about 50 plus species in this group, and some can attain a length of up to 10 feet in the wild. In captivity they usually do not exceed three feet. These animals are very tolerant of a wide range of water conditions, and violate the classic 1" of fish for every 2 gallons of water rule. The number of fish that you can successfully put into a salt water aquarium is generally placed at 1 " of fish for every two gallons of water. Well.....eels do not apply, since even at foot long eels would then require a 24 gallon tank. So one foot eel equals roughly 3 inches of fish, since most of the eel is "all tail"!

The moray eel that does fit the rule is the Zebra Banded Moray (Gymnomuraena zebra) in that it does not actively eat fishes. This common species eats almost exclusively crustaceans, since it possess small dull teeth that are only occasionally used to eat fish.

Rhinomuraena - These are the colorful ribbon eels. The blue specimens are actually juveniles of the adult black form. Ribbon eels have very enlarged nasal nares (AKA nostrils) They are defenseless, fragile and do well only if placed into well established aquarium and their food needs are attended to. They feed at dusk, so subdue the lighting and tempt them with live glass shrimp. Over time they will accept frozen fish, squid, and clams, but remember to feed them at dusk and insure that they get some food.

Myrichthys - This is the rare Golden Spot Eels. They bury themselves in the sand and are quite hardy albeit defenseless. They can be identified by their barrel shaped nostrils and large gold spot. They eat similar food as other Moray eels.