Edit Lepidosiren paradoxa

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Name

Scientific name

Lepidosiren paradoxa

Described by

Not recorded

Family

Lepidosirenidae

Common names

South American Lungfish

Photograph credits

Not recorded

Summary

The South American lungfish, Lepidosiren paradoxa, is found across the Amazon, Rio Paraguay and lower Paraná basins. The only lungfish know…

Size and aquarium

Maximum size

1250mm, standard length

Aquarium size

Minimum length 240 cm, Minimum depth 90 cm, Minimum height 150 cm, Water movement Low: still or sluggish water

Water

Water conditions

Temperature 24–28°C, pH 6–8

Hardness

2–20dGH

Conductivity

Not recorded

Behaviour

Temperament

Peaceful

Community suitability

Not recorded

Where it lives

Countries, regions, rivers and lakes

Argentina, Bolivia, Brazil, Colombia, French Guiana, Paraguay, Peru, Amazon, Paraná

Writing

Etymology

Not written yet

Distribution

It's very widely distributed in nature, and is found throughout much of the Amazon, Rio Paraguay and lower Rio Paraná basins. Populations exist in parts of Col…

Habitat

Slow moving and stagnant waters, including weedy creeks, swamps and tributaries. Many of these biotopes are hypoxic (starved of oxygen), and some are completel…

Aquarium size

A massive tank is needed to adequately house one of these. Length and width are the most important dimensions and it can actually be quite shallow if you wish.…

Maintenance

Decor is unimportant, but water movement should be kept to a minimum. Some cover can be provided in the form of roots, branches or large, smooth rocks. Ensure …

Water conditions

Temperature: 24 – 28 °C pH: 6.0-8.0 Hardness: 2-20°H

Diet

Omnivorous in nature, feeding on fish, shellfish, amphibians and plant matter. It will adapt to a variety of foods in the aquarium. Offer prawn, mussel, lancef…

Behaviour and compatibility

Generally peaceful with tankmates too large to be considered food. It can be a little unpredictable, with some specimens taking exception to other bottom-dwell…

Sexual dimorphism

Unknown.

Reproduction

Unreported in the hobby. In nature it spawns during the wet season and the eggs are deposited into a nest guarded by the male. This consists of a deep burrow l…

Notes

Lungfish are among the most intriguing of "oddball" aquarium species, being able to survive in extreme conditions. They are very ancient fish, having remained …

Lungfish are among the most intriguing of "oddball" aquarium species, being able to survive in extreme conditions. They are very ancient fish, having remained virtually unchanged for millions of years. This is the only species known from South America, and is the sole representative of its genus. Most hail from Africa, with a single species native to Australia. They belong to the class Sarcopterygii (lobe-finned fishes), members of which are actually more closely related to terrestrial vertebrates than to the Actinopterygii (ray-finned bony fishes).

Some of the natural waters of L. paradoxa dry out completely at times and the fish has developed several incredible adaptations in order to survive these periods. When the waters begin to recede, the fish will find a suitable nesting site, usually amongst heavy vegetation. Here, it will dig down into the muddy substrate, forming a tunnel. When it reaches a certain depth (this varies depending on the fish, but is typically around 12"), it writhes around until it forms a bulb shaped chamber, in which it will spend the dry season. It then positions itself in such a way that its head is pointing upwards, towards the entrance. The chamber is often filled with water initially and the fish has to rise to the entrance of the burrow to take in air. However, as the water level drops further, it becomes completely exposed to the air. At this point, it excretes copious amounts of a special mucous, which dries to form a "cocoon" around its body. It's metabolic rate also decreases drastically. There it remains, completely motionless, until the rains return. This state is known as aestivation.

Although it possesses both gills and a set of paired lungs, it's an obligatory air breather and will drown if not granted access to atmospheric air. The gills are rudimentary in structure and the fish has to rise to the surface periodically to obtain oxygen. The lungs are similar in structure to those of primitive amphibians and are formed from the heavily modified swim bladder.

The limb-like fins are long, thin and fleshy. They are used mainly for touch. However, they are supported by a strong set of muscles and allow the fish to "crawl" across patches of dry land if necessary. There are four of these, located in the same positions as tetrapod legs. Other similarities between lungfish and tetrapods include the possession of tooth enamel, the way in which the bones of the skull are arranged and the distinct separation between pulmonary and body blood flow. Unlike most other fish species, the heart has 4 distinct chambers, facilitating the latter.

It's debatable as to whether this species should be considered an aquarium subject at all given its eventual size. All too often juveniles are sold without adequate information regarding their long term care. These can and will attain something close to their maximum size in captivity, and will do so quite quickly. The myth that fish will only grow to match the size of the tank they're kept in is just that. It's also worth noting that it can live for well over 20 years, making it a considerable long term commitment. Many aquarists buy a young specimen with the intention of buying a bigger tank as it grows. However due to life's unpredictable nature very few actually take this step, instead attempting to rehome the fish. Public aquaria are already inundated with far too many 'cast offs' from the hobby, and are unlikely to take a big fish off your hands. Very few fellow hobbyists will have the facilities to do so, either. It's sad to think how many hundreds of these are doomed to a drastically reduced existence by the aquatic trade. Please don't buy one unless you have the resources requires to house it for life already in place.

Those few that do will find it to be very hardy and undemanding. Some specimens even become very tame and seem to enjoy being 'petted' by their owner. If attempting this, be aware that it can inflict a nasty bite and should be approached with caution.

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My own experienceFor example, I've kept twelve in a planted 60 cm tank since March 2024.A website I sawFor example, an IUCN Red List assessment, a museum catalogue or a FishBase page.A paperFor example, Marshall et al. (2011), Water temperature differences in interfluvial palm swamp habitats of Paracheirodon axelrodi and P. simulans.A book, or something not onlineFor example, Tappin (2010), Rainbowfishes: their care and keeping in captivity.Something already on the pageFor example, the Behaviour and compatibility section already says this.

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Name

Scientific name

Described by

Family

Common names

Photograph credits

Summary

Size and aquarium

Maximum size

Aquarium size

Water

Water conditions

Hardness

Conductivity

Behaviour

Temperament

Social needs

Community suitability

Where it lives

Countries, regions, rivers and lakes

Writing

Etymology

Distribution

Habitat

Aquarium size

Maintenance

Water conditions

Diet

Behaviour and compatibility

Sexual dimorphism

Reproduction

Notes

References

References