Protopterus aethiopicus – Marbled Lungfish

Protopterus aethiopicus – Marbled Lungfish

The African Lungfish, Protopterus aethiopicus, was first described by Johann Jakob Heckel in 1851. This fish belongs to the family Protopteridae, which contains only one genus: Protopterus. This genus includes four species. The genus name “Protopterus” is derived from the Greek “pro” (first) and “pteron” (wing or fin), which refers to the primitive fins of these fish. The species name “aethiopicus” refers to Ethiopia, one of the countries where this fish occurs.

Synonyms:

• Protopterus aethiopicus aethiopicus
• Protopterus aethiopicus congicus
• Protopterus aethiopicus mesmaekersi

Description

Appearance:
The Marbled Lungfish has an elongated, cylindrical body with smooth skin covered with deeply embedded scales. The fish has a yellow-gray or pink base with dark slate-gray spots, creating a marble or leopard pattern. The color is darker at the top and lighter at the bottom. The fins are long and thin, almost spaghetti-like. Adult specimens can reach a length of more than 200 centimeters.

Differences between males and females:
Males and females show few physical differences, although males are often slightly larger. Behaviorally, no significant differences were reported between the sexes.

Behavior and temperament:
The Marbled Lungfish is generally peaceful and can live well with other fish, provided they are not too small. They are solitary and can become aggressive if they feel threatened. They are bottom dwellers and can swim in middle waters as well as on the bottom.

They are quite inactive during the day. They are awake mainly at night. They sometimes swim wildly through the aquarium.

Life expectancy:
In the wild, Marbled Lungfish can live up to 20 years, while in a well-maintained aquarium, they can reach a similar lifespan.

Breathing

Protopterus aethiopicus, also known as the marbled lungfish, has a unique breathing method that allows it to survive both in water and on land. This species of fish is an obligate air breather, meaning it must breathe air to survive, especially when in low-oxygen environments.

Anatomy and Physiology of Respiration

The Marbled Lungfish has both gills and lungs. The lungs are developed from an outpouching of the intestine, similar to the swim bladder of other fish, and are highly vascularized with thin-walled blood vessels that absorb oxygen from the inhaled air. In adults, the gills are reduced and not sufficient to function as the sole respiratory organ, although they still play a role in carbon dioxide elimination.

Breathing behavior

Under normal conditions in well-oxygenated water, the Marbled Lungfish can largely meet its oxygen needs through aquatic respiration. However, in situations where the water is low in oxygen, such as during droughts, the fish switches to air breathing. This is done by coming to the surface and breathing in air. In laboratory conditions, it has been shown that the fish absorbs more than 90% of its oxygen through the lungs.

Aestivation

One of the marbled lungfish’s most notable adaptations is its ability to aestivate. During periods of drought, the fish burrows into the mud and forms a cocoon of mucus to prevent dehydration. In this condition, the fish can survive for months by breathing air through a small opening in the cocoon.

Research and Observations

Research using radio telemetry has shown that marbled lungfish breathe air less often in the wild than in laboratory conditions. This suggests that the frequency of air-breathing may depend on ecological and physiological factors, such as the oxygen concentration in the water, the presence of predators, and the temperature of the water.

The Marbled Lungfish is a fascinating example of evolutionary adaptation to varying environmental conditions. Its ability to breathe both aquatic and air makes it particularly suited for survival in the dynamic and often unpredictable habitats of Africa.

Moving over land

Protopterus aethiopicus has some remarkable adaptations that allow it to move over land, especially during periods of drought. The pectoral and pelvic fins of the are long and thin, almost spaghetti-like. These fins are used to move on the bottom and can also aid in locomotion over land.

Although the Marbled Lungfish is not specifically adapted to travel long distances over land, it can move over short distances using its body and fins. This behavior is usually observed when the fish needs to move to a new body of water during drought periods

There are anecdotal stories of Marbled Lungfish getting into the mud of building materials and breaking through the walls of houses to get back to the water after heavy rain. This illustrates their remarkable survivability and adaptability to changing environmental conditions.

Biotope

Distribution:
The Marbled Lungfish is native to countries such as Ethiopia, Kenya, Uganda, Tanzania, South Sudan, and Zambia. They live mainly in the rivers and lakes of these countries, such as the Nile, Congo, and Lakes Victoria, Albert, Edward, Tanganyika, and Kyoga.

Natural habitat:
These fish are often found in swampy, vegetation-rich areas of lakes and large river systems. They can also occur in open waters of lakes. The bottom of their habitat usually consists of mud, in which they can burrow during periods of drought.

Climate:
They live in a tropical climate with seasonal floods and droughts. During periods of drought, they can survive by burrowing into the mud and forming a cocoon. They also survive the complete drying out of the environment in which they live. After the first rainfall, they rehydrate and emerge from their cocoon.

Diet

In the wild:
In their natural habitat, African Lungfish feed mainly on mollusks, but also on fish and insects. The young fish mainly feed on insects.

In the aquarium:
In an aquarium, they can be fed a diet of live or frozen foods such as fish, shrimp, and insect larvae. It is important to provide a varied diet to ensure their health.

The Aquarium

Aquarium size:
One African Lungfish requires an aquarium of at least 300 centimeters and 1250 liters. For multiple specimens, the aquarium must be significantly larger.

Decoration:
The aquarium should be decorated with plenty of hiding places such as rocks and large pieces of wood. Plants can be added but must be sturdy as the fish can damage them. A sandy bottom is most suitable because the fish likes to dig in.

Water parameters:
The ideal water parameters for this fish are a pH of 6.5 to 7.5, a temperature of 25-30°C, and a water hardness of 6-16 °d.

Compatibility:
Marbled Lungfish are usually not suitable for keeping with other fish species. When they get into the spawning mood they become very aggressive towards other species.

Breeding Protopterus aethiopicus

As far as is known, breeding Protopterus aethiopicus in the aquarium has not yet been successful.

In the wild, they reproduce during the rainy season. The males make a breeding pit in the ground. He lures one or more females to the breeding pit. They lay the eggs, that are fertilized by the male. The females’s task is now over and they leave the den.

The male is responsible for protecting the nest. For eight weeks he guards the nest and protects the eggs from predators. In areas with sufficient water, they reproduce all year round. Only after three years do the fish reach adulthood and can, in turn, reproduce.

Conclusion

The Marbled Lungfish is a fascinating and unique fish species suitable for advanced aquarists. They require a large aquarium and specific water conditions, but their interesting behavior and long lifespan make them a valuable addition to a well-maintained aquarium. Keeping these fish can be challenging, but with proper care and attention, they can provide an impressive and rewarding experience.

Video

Author

John de Lange

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John de Lange