Home | Aquarium Livestock | Amphibians Masquerading as Fish – Notes on the Rubber Eel

Amphibians Masquerading as Fish – Notes on the Rubber Eel

Hello, Frank Indiviglio here.  As a child, I constantly combed the pet stores of the Bronx and Manhattan in search of the odd catfishes, lungfishes and eels I so favored.  I distinctly recall first coming upon some creatures labeled as “rubber eels”, and realizing that I was looking at something special – I just didn’t know exactly what!  The blue-gray “fish” were indeed quite rubbery in texture and did look like eels, yet something was “off”.  In time, I learned that these odd beasts were amphibians, specifically aquatic or River Cauca Caecilians, Tylphlonectes natans.

Natural History

Today, so many years later, you can still find these caecilians being sold as rubber eels.  The River Cauca caecilian is one of the  Typhlonectes natans few aquatic members of this little studied amphibian order (the Gymnophiona), and, even now, is the only one to regularly appear in the trade, or even in zoos.  They are found only within the drainages of 2 rivers systems in northern Columbia and northwestern Venezuela, and little is known of their lives in the wild.

Aquatic Caecilians in the Aquarium

River Cauca Caecilians are quite hardy when given proper care, and may even surprise you with young, which are born alive and have external gills.  I’ve bred them in a well-filtered (undergravel) 20 gallon aquarium at a pH of 7 and temperature of 76 F, but one experienced keeper advises that they fare better in acidic water, and recommends sphagnum moss as a substrate.  They may reach 24 inches in length, but most top out at 12-16 inches.

Caecilians are quite shy at first, and must be provided with subdued lighting and artificial caves, PVC pipes, live plants and the like as shelter.  Those I’ve kept have become quite bold after a time, leaving their hideouts by day when scenting the earthworms, blackworms and prawn that are their favorite foods.  A few individuals learned to take frozen foods and shrimp pellets, but live food is definitely preferable.

Fish keeping experience will serve you well in caring for these fascinating amphibians…with so much still unknown about them, I hope that more aquarists take up the challenge!

Further Reading

You can read more about this and other caecilians here.

Please write in with your questions and comments. 

Thanks, until next time,

Frank Indiviglio

Tylphlonectes natans image referenced from wikipedia and originally posted by Christophe cagé


  1. avatar

    The Tennessee Aquarium posted a nice little video of one of their caecilian’s giving birth:

  2. avatar

    I was wondering if you could email me if you ever see these for sale.

  3. avatar

    Hi Dianne, Thanks for your interest. Please contact our livestock department at 1-877-367-4377, they’ll be happy to find out if we are able to order these fascinating animals and they can put you on their notification list if we are able to recieve them.

  4. avatar


    I was asked to post here by Frank Indiviglio on Twitter for some further reading or journal articles on the family Gymnophiona and the species within this family as I am interested in brushing up on my knowledge of them! Any help would be appreciated!


  5. avatar

    Hello Joe, Frank Indiviglio here.

    Thanks for your interest in our blog. AmphibiaWeb http://bit.ly/rmdPQ1 is a great starting point. You can also search individual species for links and references on this website http://research.amnh.org/vz/herpetology/amphibia/?action=references&id=32732.

    Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

    Best regards, Frank Indiviglio.

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About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.