Monday, June 22, 2009

South American Lungfish Amazonian Lungfish Family: Lepidosirenidae

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.

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.

The species is not listed on the IUCN Red List.

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:

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.

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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  1. please use proper credit with the photos as well. many of these are from my website,
    --solomon david