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Protopterus
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African lungfish
Temporal range: 83.6–0 Ma[1] Campanian to present
Protopterus annectens
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Dipnoi
Order: Ceratodontiformes
Family: Protopteridae
Peters, 1855
Genus: Protopterus
Owen, 1839
Species
Synonyms[2][3][4]
  • Protomelus Hogg 1841
  • Rhinocryptis Peters 1844

Protopterus is the genus of four species of lungfish found in Africa. Protopterus is considered the sole genus in the family Protopteridae, which is grouped with Lepidosiren in the order Lepidosireniformes.[5][6][7][8]

Taxonomy

[edit]

The earliest fossils of the Protopteridae come from the Late Cretaceous (Campanian-Maastrichtian) of Sudan,[9] but phylogenetic evidence indicates that it and Lepidosirenidae split at the very beginning of the Early Cretaceous, around 145 Ma.[8] Together, their common ancestor diverged from the only other extant lungfishes in Neoceratodontidae during the Late Jurassic.[10]

Some papers suggest grouping Protopterus and Lepidosiren together in the family Lepidosirenidae, as their Cretaceous divergence is relatively recent compared to the Carboniferous origins of other lungfish families. However, most taxonomic authorities retain them as distinct families.[6][7][8]

Description

[edit]

African lungfish are elongated, eel-like fishes with thread-like pectoral and pelvic fins. They have soft scales, and the dorsal and tail fins are fused into a single structure. They can either swim like eels or crawl along the bottom using their pectoral and pelvic fins.[11] The largest species can reach about 200 cm (6.6 ft) in length.[4]

African lungfish generally inhabit shallow waters, such as swamps and marshes. They are also found in larger lakes such as Lake Victoria. They can survive out of water for many months by burrowing into hardened mud beneath a dried stream bed. They are carnivorous, feeding on crustaceans, aquatic insect larvae, and molluscs.[11]

Biology

[edit]
Lateral view of lungs of a dissected Protopterus dolloi
Clod of mud containing the cocoon of lung fish

The African lungfish is an example of how the evolutionary transition from breathing water to breathing air can occur. Lungfish are periodically exposed to water with low oxygen content or encounter situations in which their aquatic environment dries up. To cope with these conditions, they have developed an adaptation in the form of an outpocketing of the gut, similar to the swim bladder found in other fishes. This specialized structure functions as a lung.[11] Within the lung, numerous thin-walled blood vessels allow the blood to absorb oxygen from the air that is gulped into the lung.

They are obligate air breathers, with reduced gills in the adults. There are two anterior gill arches that retain gills, though they are too small to function as the sole respiratory apparatus, and may be more important for carbon dioxide elimination. About 90% of their oxygen is acquired via their lungs, and the remaining ~10% via the gills and skin.[12] The lungfish heart has adaptations that partially separate the flow of blood into its pulmonary and systemic circuits. The atrium is partially divided, so that the left side receives oxygenated blood and the right side receives deoxygenated blood from the other tissues. These two blood streams remain mostly separate as they flow through the ventricle leading to the gill arches. As a result, oxygenated blood mostly goes to the anterior gill arches and the deoxygenated blood mostly goes to the posterior arches.

African lungfishes breed at the beginning of the rainy season. They construct nests or burrows in the mud to hold their eggs, which they then guard against predators. When they hatch, the young resemble tadpoles, with external gills, and only later develop lungs and begin to breathe air.[11]

Spotted African lungfish, Protopterus dolloi

As food

[edit]

Until the introduction of the Nile perch to the region, lungfish typically comprised a small proportion of a fisherman's catch. Transportation to market from catching sites in Lake Victoria was often done with fish sun-dried for better preservation. Human consumption of the lungfish varies by population; the Luo peoples occasionally do so but the Sukuma avoid eating lungfish due to a taste which is "locally either highly appreciated or strongly disliked."[13] As technology advancements such as longlines and gillnets have been increasingly applied over the past 50 years, the lungfish populations there are believed to be decreasing.

Species and subspecies

[edit]
Marbled or leopard African lungfish, Protopterus aethiopicus

The family Protopteridae and genus Protopterus contain four extant (living) species:[4]

Other extinct species are known from fossil remains:

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Protopterus

View on Grokipedia
from Grokipedia
Protopterus is a of endemic to , consisting of four extant that represent the sole members of the family Protopteridae in the order Ceratodontiformes. These sarcopterygian fishes are distinguished by their moderately elongate, cylindrical bodies, which can reach up to 180 cm in length, and possess six gill arches with five gill clefts, enabling both gill and air breathing. Adapted to tropical freshwater environments such as swamps, rivers, and lakes in , Protopterus exhibit remarkable physiological tolerances, including the ability to aestivate for extended periods—up to several years—within a self-constructed mucous cocoon during seasonal droughts, drastically reducing metabolic rates to survive anoxia and . The name derives from Greek roots meaning "first fin," reflecting their primitive, lobe-like that underscore their evolutionary significance as living fossils closely related to the ancestors of tetrapods. The four recognized species—P. aethiopicus (marbled lungfish), P. annectens (), P. amphibius (), and P. dolloi (slender lungfish)—are distributed across distinct regions of Africa, from the to the and river systems, inhabiting marginal, often stagnant waters where they feed primarily on , small vertebrates, and matter. As air breathers, they surface periodically to gulp atmospheric oxygen, a trait that allows persistence in low-oxygen habitats but renders them vulnerable to and habitat alteration. Ecologically, Protopterus species serve as important predators in their ecosystems and support local fisheries, though overexploitation and environmental changes pose conservation challenges for some populations. Phylogenetically, Protopterus belongs to the subclass Dipnoi (lungfishes), forming a to tetrapods within the broader clade, providing critical insights into vertebrate evolution, particularly adaptations for terrestrial transition such as development and limb-like fins. on these fishes has advanced understanding of hypoxia tolerance, regeneration, and metabolic plasticity, with applications in and .

Taxonomy

Etymology

The genus name Protopterus is derived from the Greek words prōtos (πρῶτος), meaning "first" or "primitive," and pteron (πτερόν) or pterygion (πτέρυγιον), meaning "fin" or "wing," alluding to early 19th-century views of lungfishes as representing a basal stage in the evolution of finned vertebrates toward higher forms. The genus was established by anatomist Richard Owen in 1839, based on specimens of African lungfish initially described as a new species within the South American genus Lepidosiren, leading to taxonomic confusion as the African forms were later recognized as distinct. Common names for species in the genus include "African lungfish," reflecting their distribution and respiratory adaptations, with regional variations such as "West African lungfish" in English-speaking contexts, "Tana lungfish" in Kenya, "mudfish" in Ghana, and "Maoundé" or "Wõndo" in the Bambara language of West Africa.

Classification and phylogeny

Protopterus is classified within the subclass Dipnoi (lungfishes), order Ceratodontiformes, and family Protopteridae, of which it is the only genus. The family Protopteridae encompasses the African lungfishes, distinct from the South American Lepidosirenidae and Australian Neoceratodontidae, reflecting the biogeographic fragmentation of Gondwana. Phylogenetic analyses indicate that Protopteridae forms a monophyletic group, corroborated by molecular data including sequences that support the close interrelationships among Protopterus species. The lineage diverged from Neoceratodontidae (represented by Neoceratodus) approximately 186–195 million years ago during the to transition, based on transcriptome-based phylogenomics. Subsequently, Protopteridae split from Lepidosirenidae in the around 120 million years ago (95% : 165–94 Ma), as estimated from analyses of nuclear genes like and RAG2. The fossil record provides minimum ages for these divergences, with the earliest known Protopterus fossils from the stage (approximately 99.6–93.5 Ma) in northern (Wadi Milk Formation) and . These specimens, identified by heavy tooth plates characteristic of the , indicate that Protopterus had already diversified in by this time, consistent with the family's Gondwanan origins and subsequent isolation.

Physical characteristics

Morphology

Protopterus species possess an elongated, eel-like body shape that is cylindrical in cross-section, facilitating movement through aquatic and semi-terrestrial environments. This form is characterized by a prominent and small eyes positioned dorsally. The body is covered by small, scales that are deeply embedded in the skin, rendering them inconspicuous and contributing to a smooth, slimy surface rich in mucous glands. The paired pectoral and pelvic fins are slender, thread-like appendages that extend along much of the body length, serving as primary structures for propulsion in soft substrates. In contrast, the unpaired fins—the dorsal, caudal, and anal—are fused into a single, continuous diphycercal fin fold that encircles the posterior region, providing stability during undulatory . Protopterus exhibits a single dorsal nostril, which opens into the olfactory sac, alongside reduced slits that appear as small, pore-like openings covered by an operculum. Unlike other in the genus, P. amphibius retains three pairs of into adulthood. These features reflect the genus's to low-oxygen waters. Across species, variations occur in overall size, with lengths ranging from 44 cm in Protopterus amphibius to 200 cm in Protopterus aethiopicus, and in coloration, often featuring mottled or spotted patterns for .

Size, coloration, and sensory features

Species of the genus Protopterus exhibit considerable variation in body size, with maximum adult lengths ranging from 44 cm in P. amphibius to 200 cm in P. aethiopicus, though most species typically reach 60-130 cm. The (P. aethiopicus) is the largest, reaching a maximum total length of 200 cm and a common length of 130 cm, with a maximum recorded weight of 17 kg. In contrast, the (P. annectens) grows to a maximum of 100 cm in total length and 4 kg in weight, while the slender lungfish (P. dolloi) attains up to 130 cm. These dimensions reflect an elongated, eel-like body form adapted to their aquatic environments. Coloration in Protopterus species features mottled or marbled patterns that vary by species and provide visual distinction. In P. aethiopicus, the dorsal surface is dark slate-grey, transitioning to yellowish-grey or pinkish tones ventrally, often accented by numerous dark spots or flecks on the body and fins, with some individuals displaying bright yellow ventral regions. P. annectens typically shows a mottled pattern in , , and grey, sometimes with black or dark brown markings. For P. dolloi, the body is generally brownish or greyish, with juveniles exhibiting prominent black spots on the dorsal and lateral surfaces that diminish or disappear in adults. Sensory features of Protopterus are specialized for their often turbid, low-visibility habitats. The eyes are relatively small and adapted for dim-light conditions through the presence of oil droplets in photoreceptors, which enhance capture and sensitivity; in P. dolloi juveniles, for instance, and cones contain these droplets, supporting increased light flux over high acuity. The lateral line system includes mechanoreceptive neuromasts distributed along the head and body, enabling detection of water movements and vibrations for spatial awareness. Additionally, the skin houses electroreceptive ampullary organs, which detect weak for prey localization in murky waters; in P. dolloi, these ampullae feature receptor cells with club-shaped apical protrusions instead of kinocilia.

Habitat and distribution

Geographic range

The genus Protopterus, comprising four extant species of African lungfish, is endemic to freshwater systems across , with no natural occurrences outside the continent. These species inhabit a variety of rivers, lakes, swamps, and floodplains, primarily in tropical and subtropical regions south of the Sahara Desert. In western Africa, Protopterus annectens predominates, ranging from and in the west to and in the east, including major basins such as the Volta, , Bandama, and Comoé rivers. This species extends southward into central and , with subspecies like P. a. brieni found in the middle and lower River, , and lakes such as , Mweru, and Bangweulu, spanning countries including , , , , and . In central , Protopterus dolloi is restricted to the basin and adjacent systems, including the Ogowe, Kouilou-Niari, and Loeme basins in , , , and . Eastern Africa hosts Protopterus aethiopicus and Protopterus amphibius, with P. aethiopicus distributed across the River system, including lakes Victoria, Albert, , Kyoga, Turkana, and Tanganyika, as well as the upper in countries like , , , , and . Meanwhile, P. amphibius occupies coastal swamps and floodplains from and southward to the Delta in , with records also from the Lake Rukwa basin and Ruaha River plains in . Although limited human-mediated introductions have occurred, such as P. annectens brieni into in and P. aethiopicus into Lake Mohasi in , no successful establishments outside are documented. The genus's distribution reflects historical stability, with fossil records indicating origins in peri-equatorial during the , followed by dispersal across the continent during the without evidence of major range shifts beyond . Habitat degradation from and human activities may pose risks to some populations, though overall ranges remain extensive as of 2025.

Environmental preferences and ecology

Protopterus species primarily inhabit shallow, vegetated freshwater systems, including swamps, marshes, and seasonal rivers, where they are associated with aquatic macrophytes such as papyrus (Cyperus papyrus) and water hyacinth (Eichhornia crassipes). These environments provide cover and breeding sites, with preferred water conditions including pH levels of 7–9 and temperatures ranging from 24–28°C. The genus is distributed across tropical , from West African river basins to East African lakes like Victoria and Kyoga. As obligate air-breathers, Protopterus exhibits high tolerance to low dissolved oxygen levels (as low as 1–3 mg/L) and high typical of their muddy, vegetated habitats, relying on pulmonary respiration to supplement or replace gill-based oxygen uptake. During seasonal floods, individuals migrate to shallow swampy areas within lakes or river systems for breeding and feeding. In their ecosystems, Protopterus serves as an opportunistic predator, contributing to dynamics by preying on such as mollusks, crustaceans, and insects, thereby helping to regulate populations of disease-vectoring snails like those transmitting . Their burrowing in substrates facilitates interactions with co-occurring , including microbial communities that may aid in nutrient cycling during periods of habitat stress.

Physiology and life history

Respiratory and metabolic adaptations

Protopterus species are obligate air-breathers, relying primarily on paired, vascularized lungs derived from the for . These lungs feature and extensive vascularization, enabling efficient oxygen uptake from air, which accounts for approximately 90% of total oxygen acquisition, while the gills and contribute the remaining 10% in aquatic environments. The gills are greatly reduced, with fewer arches and absent secondary lamellae in some species, and the operculum is minimally developed, reflecting an evolutionary shift toward aerial respiration. Air is drawn into the lungs via a buccal force pump mechanism, where expansion of the oropharyngeal cavity aspirates air through the nares, followed by compression to propel it posteriorly into the lungs. During periods of environmental stress, such as , Protopterus exhibits profound adaptations to conserve and manage waste products. Metabolic rate decreases significantly, with downregulation of genes in alveolar cells, leading to reduced oxygen consumption. metabolism shifts to favor synthesis over ; initially, accumulation increases up to 2.8-fold to detoxify , serving as both an osmoregulator and a less toxic waste product that builds to levels five times higher than in active . Over prolonged , is suppressed by up to 84%, minimizing the energy demands of synthesis and preventing . In hypoxic aquatic conditions, Protopterus demonstrates tolerance through a metabolic switch to anaerobic pathways, relying on stores like for ATP production via less efficient , while suppressing overall to extend survival. Hepatic and muscular energy status is maintained by reducing reliance on breakdown, allowing the to endure low-oxygen until air-breathing can resume.

Reproduction and development

Reproduction in Protopterus species is closely tied to the rainy season, when flooded swamps and shallow waters provide suitable conditions for spawning, typically occurring from October to March across their African range. Males construct nests in the form of U-shaped burrows or pits excavated in mud or among dense such as roots, often reaching depths of up to 60 cm, with the nest chamber approximately 20-30 cm in diameter to accommodate eggs and early larvae. Fertilization is external, with females entering the male-guarded nest to lay eggs, which the male then fertilizes. Clutch sizes vary by species and female size, ranging from several hundred to over 5,000 eggs, which are white and approximately 4 mm in diameter. Males provide extensive , guarding the nest against predators, fanning oxygenated water over the eggs and larvae using their mouths and fins to maintain adequate oxygen levels in the often hypoxic nest environment, and continuing this protection for about 8 weeks until the young disperse. Upon hatching after about 8 days, larvae exhibit a tadpole-like morphology, featuring three pairs of external, ciliated gills for aquatic respiration and a yolk sac for initial nourishment; they begin air-breathing at around 23-25 mm in length. These external gills facilitate convective currents for oxygen uptake and persist for 4-6 weeks, during which larvae remain in the nest under male protection for 50-55 days at temperatures around 23°C. Metamorphosis follows, with external gills undergoing necrosis and resorption as internal gills and lungs fully develop, transitioning the young to juvenile forms capable of independent air-breathing and foraging. Juveniles grow rapidly in the post-metamorphosis phase, reaching at lengths of 30-40 cm after 2-3 years, though this varies by species (e.g., smaller in P. annectens at ~30 cm and larger in P. aethiopicus at 70-76 cm). Overall lifespan exceeds 10 years in the wild, with some individuals potentially surviving over 20 years in captivity, supported by their adaptations to periodic .

Behavior

Feeding habits

Protopterus species are predominantly carnivorous, preying on small , crustaceans such as and crabs, insect larvae, and mollusks, though they occasionally consume plant material and detritus, reflecting opportunistic omnivory. In , for instance, mollusks dominate the diet of P. aethiopicus at 94.3% by volume, followed by remains at 4.9%, with minor contributions from insects and higher . This benthic-oriented feeding strategy targets abundant bottom-dwelling organisms in swampy and habitats. Foraging occurs primarily through suction feeding, where rapid hyoid depression and lower rotation create negative pressure to draw in prey, aided by a protrusible that enhances capture efficiency without significant jaw protrusion. Strikes are relatively slow, averaging 273 ms to peak gape, suited to non-evasive benthic prey like worms and mollusks. Activity peaks at and continues nocturnally in shallow waters, allowing exploitation of low-light conditions for predation. Dietary composition varies seasonally, with increased piscivory during wet periods when floodplains provide access to small schools, and a reliance on like crustaceans and mollusks in the as habitats contract. Diet breadth tends to expand in the due to resource scarcity, promoting flexibility in prey selection. This adaptability supports amid fluctuating water levels. The low metabolic rate of Protopterus enhances feeding efficiency by minimizing energy demands between meals, permitting extended fasting periods during , lasting months to several years, without nutritional intake.

Aestivation and survival strategies

Protopterus species, known as African lungfish, employ as a primary to endure prolonged periods of in their seasonal aquatic habitats. During the , individuals burrow into the moist of drying riverbeds or swamps, excavating tunnels up to 50 cm deep before curling into a spherical position with the mouth oriented toward the surface. This burrowing behavior allows them to escape and extreme temperatures, with the process typically beginning as water levels recede. Once positioned, the secretes copious from specialized glands, which hardens into a protective cocoon enveloping the body except for a small opening at the for aerial respiration. Recent studies have shown that the cocoon consists of layered living epithelial cells, providing additional defense beyond minimizing water loss. This airtight barrier minimizes water loss and provides a physical shield against environmental stressors, enabling survival for up to one year or longer in some cases without food or water. The cocoon's formation is gradual, taking 1-2 weeks as the surrounding mud dries, and it relies on the 's air-breathing capability through lungs to sustain minimal oxygen needs. Physiologically, induces profound metabolic depression, with heart rate dropping from 22-30 beats per minute in aquatic conditions to 11-16 beats per minute or lower during maintenance, alongside reduced activity to conserve energy. Energy demands are met primarily through stored body fats, while an active ornithine-urea cycle detoxifies by converting it to , accumulating it in body fluids to maintain osmotic balance and prevent toxicity. Emergence from aestivation is triggered by the onset of heavy rains, which soften the cocoon and signal environmental recovery. Upon water contact, the rapidly rehydrates through cutaneous absorption, primarily via the highly vascularized ventral skin surface, restoring body volume and electrolyte balance within hours; the cocoon sloughs off within 1 hour, and normal activity resumes in 24 hours or less. This process reverses the hypometabolic state, reactivating metabolic pathways. Additionally, the cocoon's earthy, mud-like coloration and texture provide cryptic , blending seamlessly with the surrounding substrate to deter predation by visually hunting animals during the vulnerable burrowed phase.

Species

Extant species

The genus Protopterus comprises four extant species of African lungfish, all obligate air-breathers adapted to freshwater environments with seasonal drying. These species exhibit habitat specialization across sub-Saharan Africa, with variations in body size, coloration, and minor morphological traits such as fin structure and scale patterns. Protopterus annectens, known as the West African lungfish, is distributed across West and Central Africa, including the Sahelian basins from Senegal to the upper Congo River, middle and lower Zambezi River, and east coast rivers up to the Limpopo, as well as Lake Rukwa. It inhabits marginal swamps and backwaters, reaching a maximum length of 100 cm total length (TL) and weight of 4 kg. Two subspecies are recognized: P. a. annectens in western ranges and P. a. brieni in eastern ones. Protopterus aethiopicus, the , occurs in East and , primarily in the (including lakes Albert, Edward, Victoria, Nabugabo, Tanganyika, Kyoga, No, and Turkana) and the from the upper Lualaba to . It features a smooth, cylindrical body with a marbled pattern of dark slate-grey above and yellowish-grey or pinkish below, often spotted, and can grow to 200 cm TL and 17 kg. Three exist: P. a. aethiopicus in eastern lakes like Victoria, P. a. congicus in the upper Congo, and P. a. mesmaekersi in the lower Congo. Protopterus amphibius, or , is found along East African coastal regions from and to the River delta, with reports from the Lake Rukwa basin and floodplains of the Ruaha and lower Rufiji rivers (though some southern records require confirmation). It is the smallest species, attaining a maximum of 44 cm TL, and uniquely retains functional and well-vascularized anterior fins into adulthood among Protopterus species, supporting prolonged aquatic respiration. Protopterus dolloi, the spotted or slender , is endemic to , widespread in the lower and middle basin, as well as the Ogowe, Kouilou-Niari, and Loeme rivers. It has a more elongate, cylindrical body than congeners, with filamentous pectoral and pelvic fins and a spotted pattern aiding in riverine ; adults reach up to 130 cm TL and 11 kg. Although its rarely dries completely, P. dolloi can aestivate in a cocoon like other species; it also digs tunnels for .

Fossil species and extinct forms

The fossil record of Protopterus documents the genus's presence in since at least the , with remains primarily consisting of robust tooth plates that distinguish it from other dipnoans. Several species or forms have been identified from deposits ranging from the stage of the (~99–93 Ma) to the , reflecting a period of diversification followed by relative stability. These fossils, often found in northern and eastern African sedimentary basins, provide key evidence for the evolutionary history of African lungfishes, highlighting their to freshwater environments over tens of millions of years. Notable extinct species include Protopterus crassidens, described from tooth plates exhibiting three prominent ridges and thick, crushing cusps, recovered from the Late Cretaceous Mut Formation in the eastern Dakhleh Oasis of Egypt's Western Desert. This species, dating to around 83 Ma, represents one of the earliest definitive records of the genus and suggests early occupation of North African aquatic systems. Another example is Protopterus elongus from Eocene deposits (~50–34 Ma) in Mali, characterized by a shorter posterior tooth ridge and perpendicular pterygoid processes, indicating morphological variation possibly linked to dietary adaptations in Tertiary freshwater habitats. Protopterus libycus, known from Late Cretaceous sites in Libya, further underscores the genus's initial northern African distribution before southward expansion. The fossil record reveals early diversification in northern during the , with subsequent dispersal to peri-equatorial regions, including systems, by the . This pattern aligns with vicariance events separating African Protopterus from South American lepidosirenids around 120 Ma, emphasizing the genus's ancient roots within sarcopterygian fishes. Transitional forms in the broader lineage exhibit more developed fin structures akin to early limbs, supporting Protopterus's position as a key sarcopterygian offshoot, though genus-specific fossils are limited to dental elements. No extinctions of Protopterus species are recorded after the , with modern forms achieving their current distribution by the late and remaining morphologically stable thereafter.

Human interactions

Culinary and economic uses

Protopterus species, particularly P. aethiopicus in and P. annectens in the , are harvested primarily for local consumption and trade in East and . Annual catches of African lungfish in Ugandan waters, including , exceeded 3,000 tons in the but declined to approximately 154 tons as reported in district records up to 2010. In the , P. annectens supports similar subsistence fisheries, though quantitative harvest data remain limited. methods typically involve hooks and gillnets, often conducted by specialized local fishermen targeting aestivating individuals in mud cocoons during dry seasons. The is processed by sun-drying or to extend and facilitate , with women playing a key role in these activities across communities. Common culinary preparations include boiling, frying into pieces, or incorporating into soups, accounting for a significant portion of market products such as fried items (54%) and (28%). Nutritionally, Protopterus provides high-quality protein and is rich in omega-3 fatty acids like EPA and DHA in muscle tissue, contributing to dietary needs in protein-scarce regions. However, its strong, muddy flavor leads to avoidance by certain groups, such as the Sukuma around and Shinyanga in . Economically, Protopterus supports subsistence livelihoods for many rural households, providing income through local markets and occasional exports of dried products. In , minor aquaculture trials using pond systems and formulated feeds have shown promise for cultivation, aiming to supplement wild catches amid declining natural stocks. Culturally, the holds significance as a among groups like the in Uganda, symbolizing resilience and featured in traditional beliefs.

Conservation status

All four extant species of Protopterus are currently assessed under the as of Version 2025-1, with P. aethiopicus, P. amphibius, P. annectens, and P. dolloi classified as Least Concern based on evaluations from 2009 to 2019, reflecting their wide distributions and lack of major global threats at the time. However, local populations, particularly of P. aethiopicus in the Basin, face heightened risks, with no formal regional Endangered designation but evident severe declines attributed to intense exploitation. Major threats to Protopterus species include through methods like and hook-and-line capture during , leading to targeted removal of aestivating individuals from mud cocoons; habitat loss from agricultural expansion and dam construction that alters floodplains and wetlands; from urban and industrial effluents; and competition or predation from such as the (Lates niloticus) in . exacerbates these issues by disrupting seasonal wet-dry cycles essential for breeding and , potentially reducing suitable habitats in variable riverine systems. Population trends vary regionally: stable or unknown in the for species like P. dolloi and P. annectens due to vast, less-impacted ranges, but sharply declining in the Basin, where P. aethiopicus catches dropped from 67.5 kg/ha in 1973 to 5.5 kg/ha by 1986, representing over 90% reduction in surveyed areas, with continued pressure into the from escalating effort. No species-specific protections exist, though habitats overlap with Ramsar sites such as Lutembe and Sango –Musambwa Island–Kagera on , which safeguard critical and breeding grounds through broader wetland conservation. Ongoing research priorities include comprehensive post-2023 population surveys to update trends amid climate variability and fishing intensification, particularly in under-monitored areas like the , alongside development of aquaculture protocols to promote sustainable harvesting and reduce wild capture pressure, as demonstrated by pilot pond culture trials in showing viable growth on formulated feeds.

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