South American Lungfish: Care, Behavior, Conservation

The Unique South American Lungfish

The South American lungfish (Lepidosiren paradoxa) is a fascinating species of fish with some very unique attributes. These ancient fish have primitive lungs that allow them to breathe air and survive out of water for extended periods of time. They are found inhabiting swamps and slow-moving waters in the Amazon, Orinoco, and Paraguay river basins of South America.

Natural History of Lungfish

Lungfish belong to an ancient group of fish that fossil records show existed over 380 million years ago. They are believed to be closely related to the ancestors of modern tetrapods, having evolved the ability to breathe air through primitive lungs. There are only six species of lungfish left worldwide.

The South American lungfish can grow up to 1.2 meters (4 feet) long. Their slender bodies are covered in scales, they have paired fins and fan-like pectoral and pelvic fins. One of their most unusual features is their mouth - lungfish have an upward-facing mouth lined with teeth to allow them to surface and gulp air.

Breathing Through Primitive Lungs

Unlike most fish, lungfish can breathe through lungs as well as their gills. Their lungs are thought to have evolved from the swim bladder common to most fish species. When water levels start receding during the dry season, lungfish use their fins to bury themselves in the mud where they estivate for months until water levels rise again.

During estivation, their gills are non-functional out of water. Instead, lungfish rely on their vascularized lungs to breathe air. By surfacing to gulp air every few weeks, they can obtain sufficient oxygen to keep their metabolism ticking over during the dry season.

Diet and Feeding

South American lungfish are omnivorous, feeding on plants, insects, crustaceans, mollusks, and small fish. They use their strong jaws and teeth to crush food items. In captivity they can be fed foods like shrimp, earthworms, aquatic vegetation and spirulina algae tablets.

Young lungfish start out feeding on tiny aquatic organisms. Adults tend to shift their diet towards terrestrial vegetation and seeds as they grow larger.

Availability in the Pet Trade

South American lungfish are rarely found for sale in the ornamental fish trade. Their large adult size, unusual appearance and demanding care requirements make them unsuitable for most hobby aquarists.

They should only be housed by experts with specialized lungfish setups. However, every so often captive-bred juveniles do become available from specialist breeders or fish farms. Prices range from $150-300 for specimens around 6-12 inches long.

Housing South American Lungfish

Despite being found in slow moving waters in the wild, lungfish do best in aquariums with strong water flow and robust filtration. Sand substrate is recommended as lungfish love to bury themselves.

As lungfish grow very large and produce a lot of waste, they require heavy-duty, oversized filtration systems and regular partial water changes. Well-planted set ups can also aid water quality.

Care Difficulties

In addition to massive aquariums (500 gallons plus recommended), South American lungfish can be challenging captives due to their powerful nature and carnivorous tendencies. Tank decor needs to be robust enough to withstand their strong jaws.

Water parameters must be pristine to support good health. Lungfish are also excellent escape artists – their aquarium lids must be completely secure.

This species should only be housed alone due to their predatory instincts towards tank mates. Juveniles may be kept with very large, fast fish that are too big to consume.

Conservation Status

Fortunately, South American lungfish are listed as Least Concern on the IUCN Red List. Their widespread distribution across several major South American river basins gives them a broad habitat range to occupy.

However, some localized threats include pollution, overcollection for food, and drainage or modification of swamps and wetlands across their native regions. Their estivation habits do make them vulnerable if water sources are disrupted.

In summary, the South American lungfish is an unusual ancient species that makes for a fascinating display animal. But only experienced aquarists should ever take on the challenge of meeting their extensive care needs.

FAQs

How big do South American lungfish grow?

South American lungfish can reach up to 1.2 meters (4 feet) in length as adults. They require exceptionally large aquariums of 500+ gallons.

What do lungfish eat?

Lungfish are omnivorous, feeding on plants, insects, crustaceans, mollusks and small fish. Juveniles start out preying on tiny aquatic life before shifting to more plant matter as they mature.

Can lungfish survive out of water?

Yes, lungfish have the incredible ability to estivate out of water for months at a time during dry seasons. They use their primitive lungs to breathe air while buried in mud, lowering their metabolism until water returns.

Are South American lungfish suitable aquarium pets?

No, South American lungfish require highly demanding, specialized care beyond most hobbyists. They need huge tanks with tight-fitting lids, strong water flow, and heavy-duty filtration to thrive. Even experts should house them alone.