A quick glance on a snake-like fish wriggling at the bottom of the aquarium will immediately relate our thoughts to “Eels” as they are the only fish known to exist with the shape of elongated body. But however, little do we realize that there are actually various types of species belonging to different fish family in existence and the article here is meant to share the information and find out about this extraordinary creature.
Eels belong to a large, diverse group of fishes classified under the order Anguilliformes. There are few hundreds species among the same family, some of which survives in freshwater and brackish water conditions while there are others which are saltwater. Because of their diversity, identifying and discussing each and every one of them is almost impossible and basically to make it short, there are those which are considered normal true eels but there are also some which are not eels at all although they actually look almost the same. For our discussion here, we will exclude kuhli loaches as they are not related or part of the eel family at all. Perhaps some of the most popular which are commonly heard that arouses the interest of aquarist are the American Eel and Moray eel which we shall go into details here.
American Eels (Anguilla rostrata)
This is one of the most fascinating creature in terms of its breeding behavior and they are popular among anglers as these eels are often caught and consumed as delicacies at dinner tables. The fish show some interesting life cycle as the adult eels undergo different stages and observe changes in its physical appearance from a glass like transparent eel to become a yellow adult fish. The sexually mature eels which can be found living in brackish swamps up to freshwater streams and rivers will travel to deep sea and ocean in order to spawn and produce young fry. After spawning, the parents will die at the sea and for the young eels, once they reach a certain maturity age, they will again migrate from the deep sea where they were born, to return to the places from where their parents originate.

Moray Eels (Gymnothorax)


Other types of Eels-like creature but not true eels (these are often thought to be part of the eel family)
Electric Eels (Gymnotidae)

Electric eels are freshwater species and a normal, full-grown adult fish can actually attain very large size often reaching at least 5 feet in length. A word of caution though, a fish that large is enough to stun and demobilize a horse causing temporarily paralysis, thus you can imagine what the effect would be like if you are not careful and ended up being a victim.
Hagfish with some call it Slimy or Blind Eel (Myxiniformes)
The hagfish which is a saltwater species is often considered to be an ugly fish due to its mouth region that is surrounded by pairs of barbels. Some even describe their personal experience when encountering the fish as being gross because of the amount of slime that it produces which is basically a defensive mechanism to discourage predators from eating it and then allowing it to escape from the clutches of its captors. However, certain species of the fish are still enjoyed and served as delicacies.
Spiny Eels
Peacock, Tire Track and Fire eels are among the few examples belonging to this group. Again because of what they look like with their long cylindrical body, these eels-like creatures are often thought to originate from the eel family. The fire eel for example is native to the South East Asian countries in particular Vietnam and Thailand and they are known to be kept in large tanks with the presence of bigger size tank mates as their companion. They are brightly colored and their favorite foods basically comprises of crustaceans and worms.