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South American Lungfish

Amazonian Lungfish Family: Lepidosirenidae

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Lepidosiren paradoxa Photo © Animal-World: Courtesy Ken Childs

   The South American Lungfish may not be pretty, ...but it is pretty amazing!

   As its name implies the South American Lungfish actually does have lungs and needs to breath air. The young fish can be quite pretty with gold spots on a black background. As the fish grows, this color will fade to gray or brown.

   This fish lives in swampy areas that have the potential to completely dry up during the dry season. When most of the water has dried up and all that is left is mud, it will burrow down leaving 2 or 3 small holes for breathing. A layer of mucous will form around its body to help seal in moisture. During this hibernation, its metabolism will decrease greatly, allowing it to survive for months underground. When the rains come again, it will come out of the mud to resume its life as a fish.

For more Information on keeping freshwater fish see:
Guide to a Happy, Healthy Freshwater Aquarium

Distribution:
   The South American Lungfish, also known as the Amazonian Lungfish, was described by Fitzinger in 1837. The are found in swampy areas throughout the Amazon, Paraguay and lower Paraná River basins.

Status:
   The species is not listed on the IUCN Red List.

Description:
   The body of the South American Lungfish looks rather eel like, being elongated and slender. Their pectoral fins are thin and thread-like, and their pelvic fins are a bit larger and set far back on the body. The newly hatched young look similar to tadpoles, but have branched external gills much like those of newts. After 7 weeks the young transform (called metamorphosis) into the adult form, loosing the external gills for gill openings.
   Overall, adults have a dark gray or brown coloration. Juveniles will have gold spots on a black background. As the fish grows, this color will fade to gray or brown.

Size - Weight:
   These fish can grow to over to 4 feet long (125 cm).

Care and feeding:
   The South American Lungfish may be considered omnivores as it has been fairly recently reported that they do ingest some unidentified algae and plant stems. However, they are primarily carnivorous and will eat all types of protein foods. The easiest source of food is fish; live, dead or in pieces. They will also eat insects, shrimp, crayfish, clams or most any living animal that is not quick enough to escape their vacuum like mouth. Tongs can be used to hold food in front of them to make sure it is eaten quickly and won’t have a chance to foul the water.
   Housing for this fish only needs to be large enough so that it can stretch out completely. They are not particularly active so a 60 gallon tank should be big enough for most home grown specimens. Lots of swimming space is not necessary. Ideally they like a lots of hiding places with dense vegetation along with some roots and rocks. However this fish must be able to reach the surface to breathe, so make sure the water’s surface is clear of obstructions or else they will drown.

Water Region: Top, Middle, Bottom:
   Other than when it is breathing, it will spend most of its time on the bottom of the tank.

Acceptable Water Conditions:
   Temp: 75 - 82° F (24 - 28° C)

Social Behaviors:
   They aren’t aggressive but may try to eat anything that will fit into their mouths. Although other large fish may survive in the tank with them, there is always the chance that the lungfish may attack or be attacked by other fish. In the case of the lungfish, this will not be caused by aggression but by hunger. Any fish that holds still long enough, including other lungfish, may end up with missing fins.

Sexual Differences:
   Unknown.

Breeding/Reproduction:
   Has not been bred in captivity. In the wild, adults construct tunnel type holes in the mud that they line with vegetal matter. They then retreat into the tunnel and seal it off. During breeding season the adults do not breath through their lungs, so do not need to go to the surface for air. Rather they breath through use of their gills and through many thin-branched appendages which develop temporarily during this time.
   The eggs are laid in the tunnel and guarded by the male, even after the eggs hatch into larvae. When newly hatched the young resemble tadpoles. During the larvae stage they breath through thread-like external gills, much like those of newts. After 7 weeks the young transform (called metamorphosis) into the adult form, loosing the external gills for gill openings.

Availability:
   The South American Lungfish are commonly available but this is not a fish that many stores will carry on a regular basis. It is definitely a candidate for a special order.

Author: Ken Childs
Additional Information: Clarice Brough, CFS

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Latest Comments
My lungfish is 12 yrs old now. He/she is about 1 1/2 ft. long in a 20 gallon tank. She still eats newborn rats and earthworms regularly. I got a tank divider and separated a small corner of the tank off and put in a couple of orange cichlids, two albino corys and a plecostamous. My 2 and 3 year old, whom are facinated and respectful to the fish and who help feed him, messed up the divider. I am left with one cichlid and the plecostamous. I just wanted another creature to look at. I've put bullfrog tadpoles in there for fun, but they can't handle the warm temperature that my lungfish enjoys. She has so much personality. She likes stalking the cichlid in the corner by staring at it even though they say he's blind. She also likes to rearrange the furniture in the tank sometimes by sucking up the quartz gravel in her mouth and piling it up in different locations. I use slate to make tunnels for her, but she knocks them down a lot. Laura 2009-06-30
My lungfish has gotten huge! btw...it's favorite food is snails, watch out! gaeamonster 2009-06-21
I just recently got a new lungfish. It is only a little baby it's name is Baxy (pronounced Baa z eye)I like him/her alot. They have such a cool life style and the way they eat is soo amazing. My lungfish eats soft krill pellets and very much enjoys them. The only thing I am keeping him/her with is a marble bristle nose plecostomus and a snail. He/she is in a ten gallon right now because of how small he/she is. It is also a low current tank with alot of live plants that he/she loves to hide in. Turtle Girl 2009-05-22
I've had my Lungfish for about 4 years. He's about 2ft long now. I feed him large night crawlers. I have been bitten by him before but it was a miss when he was going for food and he immediately went to the back corner; he knew he'd been bad. He's in a relatively small tank (30L) with two large angelfish. The angels are about 4 inches tall without the fins, much larger than the mouth of the Lungfish. This turned out to be a bad idea... I'm short one angel now and have a very dirty aquarium. Probably gonna keep him in his own tank. These are very easy creatures to keep and have alot of personality but best kept alone! joe 2009-02-09
Ive had one of these for a few years. He was named Jeremy by a friend of mine who worked with me at the aquatics. He is just over 2 feet long and right now lives happily in a Juwel Rio 180 with an oscar, a golden severum and a couple of plecs. I may move him to a larger tank with perhaps some tinfoils and silver shark since they are mostly surface feeders and move too quickly for him but for now he's happy with the misfits. Atkin 2008-03-18
Some of the coolest comments:
I have had mine for almost 11 years! He ate all of my tropical fish when I first got him or her from the pet store. He has killed a giant catfish as well as another lungfish over the years. He mostly eats live baby rats. Sometimes he eats nightcrawlers, grubs, goldfish, frozen or dry fish food if I am out of stuff, and has had chunks of fresh caught salmon. He lets me hold him. He drew blood in my finger as well as my 2 year old son's finger--scary more than painful. He got out of the tank once for maybe a half an hour and was okay. My 2 toddlers let me know. Laura 2008-07-25

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