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Threadfin

Threadfins (family Polynemidae) are a group of ray-finned fishes distinguished by their elongate, filamentous lower pectoral-fin rays, which give the family its common name.^[1] These perciform species, numbering approximately 40 in eight genera, are primarily marine but also occur in brackish estuaries and some freshwater habitats.^[2] Native to tropical and subtropical waters worldwide, threadfins typically inhabit coastal areas, river mouths, and mangroves over sandy or muddy bottoms, where they play key ecological roles as predators of small invertebrates, crustaceans, and fishes.^[3] The family's diversity spans Indo-Pacific, Atlantic, and eastern Pacific regions, with notable species including the Atlantic threadfin (Polydactylus octonemus) and the king threadfin (Polydactylus macrochir), both of which are oviparous with pelagic eggs and larvae.^[4] Threadfins are commercially significant in tropical fisheries, particularly in Southeast Asia, the Middle East, and West Africa, where they are harvested for human consumption due to their mild-flavored, white flesh.^[5] Additionally, they support recreational angling and serve as important bait fish in trap and line fisheries. As of 2001, annual global catches were about 93,000 metric tons.^[4] Ecologically, threadfins contribute to coastal food webs as mid-level predators and nursery-dependent juveniles, with many species showing strong site fidelity to estuarine habitats for spawning and early development.^[6] Conservation concerns arise from overfishing and habitat degradation in mangroves, prompting management measures such as size limits and seasonal closures in regions like Australia and Indonesia.^[7]

Taxonomy

Classification

Threadfins are classified in the family Polynemidae, which belongs to the kingdom Animalia, phylum Chordata, class Actinopterygii, subclass Teleostei, series Percomorpha, order Carangiformes, and suborder Pleuronectoidei.^[2]^[8] Historically, the family was placed within the order Perciformes and suborder Percoidei based on morphological characteristics shared with other percomorph fishes, such as fin ray counts and body form.^[9] However, molecular phylogenetic analyses using mitochondrial and nuclear DNA sequences have revealed paraphyly in Perciformes, leading to the reassignment of Polynemidae to Carangiformes, where it forms part of a clade including flatfishes (Pleuronectoidei) and other carangimorph groups, supported by shared genomic markers and pectoral girdle specializations.^[10] Diagnostic traits defining the family at this level include the bifurcated pectoral fin, with the upper lobe containing attached rays and the lower lobe featuring 3–7 (rarely more) elongated, detached filamentous rays that extend below the pectoral base and serve tactile functions in muddy or sandy environments.^[11] Additional family-level features encompass an inferior mouth, separated dorsal fins, subabdominal pelvic fins with one spine and five soft rays, and 24–25 vertebrae.^[2] The family currently encompasses 9 recognized genera and around 40 species, reflecting recent taxonomic revisions based on integrated morphological and molecular data.

Genera and species

The family Polynemidae encompasses nine recognized genera and approximately 42 species, primarily inhabiting tropical and subtropical marine, brackish, and occasionally freshwater environments worldwide. Taxonomic understanding has advanced through morphological analyses and molecular phylogenies, revealing polyphyly in some groups and prompting revisions such as the erection of new genera.^[8] The genera vary in size and distribution, with Polydactylus being the most speciose. Etymologies often derive from Greek or Latin roots referencing the characteristic thread-like pectoral-fin rays, while distinguishing features include the number and configuration of these free rays (typically 3–7, but up to 10 in some), body scalation, and fin morphology. For instance, Eleutheronema features four pectoral rays and is noted for its large size, up to 2 m in length. Synonymies are common due to historical misidentifications, such as multiple names applied to Polynemus species before revisions. Post-2000 genetic and morphological studies, including those by Motomura et al., have described new species within Polydactylus and highlighted its non-monophyly, leading to taxonomic splits; a 2022 ultraconserved elements phylogeny confirmed this polyphyly across multiple lineages.^[12]^[12] In 2025, the genus Filistriatus was established for small- to moderate-sized threadfins previously placed in other genera, based on genomic data from museum specimens, with its type species exhibiting grooved pectoral rays and distinct scalation patterns. Other revisions include the validation of Parapolynemus with additional species from Indo-Pacific waters. The table below summarizes the genera, approximate species counts (based on current catalogs), and type species.

Genus	Approximate Number of Species	Type Species
Eleutheronema	3	Eleutheronema tetradactylum (Shaw, 1804)
Filimanus	6	Filimanus heptadactylus (Cuvier, 1829)
Filistriatus	1	Filistriatus sexfilis (Valenciennes, 1831)
Galeoides	1	Galeoides decadactylus (Günther, 1860)
Leptomelanosoma	1	Leptomelanosoma indicum (Shaw, 1804)
Parapolynemus	2	Parapolynemus verekeri (Playfair, 1867)
Pentanemus	1	Pentanemus quinquarius (Linnaeus, 1758)
Polydactylus	15	Polydactylus virginicus (Linnaeus, 1758)
Polynemus	12	Polynemus paradiseus (Linnaeus, 1758)

Representative species include the diamond threadfin, Filistriatus sexfilis (formerly Polydactylus sexfilis), distributed in Indo-West Pacific waters and assessed as Least Concern by IUCN due to its wide range despite local fisheries pressure. Eleutheronema tetradactylum, the fourfinger threadfin, is a large Indo-Pacific species reaching 1.8 m, with regional assessments classifying it as Endangered from overfishing, though globally not evaluated. These examples illustrate the family's diversity, with many species facing conservation challenges from habitat degradation and exploitation.^[12]^[13]^[8]^[14]

Evolutionary history

The earliest evidence for the origins of threadfins (family Polynemidae) comes from molecular clock estimates, placing the most recent common ancestor of the family in the Paleogene period around 52.81 million years ago (MYA), during the late Eocene to early Oligocene.^[15] This timeline aligns with the broader diversification of percomorph fishes following the Cretaceous-Paleogene extinction, though direct fossil records for Polynemidae remain scarce and primarily limited to otoliths and fragmentary remains from the Neogene. Primitive forms within the family likely emerged in tropical marine environments, with no confirmed Eocene fossils identified to date.^[16] Phylogenetic analyses using molecular data, including ultraconserved elements and mitochondrial loci from studies in the 2010s and 2020s, have resolved Polynemidae as a monophyletic clade within the order Carangiformes, positioned as sister to the Pleuronectoidei (flatfishes).^[17] These genomic datasets, encompassing multiple genera, indicate that diversification accelerated during the Neogene period (approximately 20-2.6 MYA), with six species within the family diverging between 11.7 and 20.05 MYA. Basal genera such as Polynemus and Eleutheronema represent early branches in this phylogeny, reflecting adaptive radiations in Indo-Pacific coastal habitats.^[15] A key evolutionary innovation in threadfins is the development of elongated, thread-like pectoral-fin rays, which evolved as tactile appendages for foraging in shallow, low-visibility waters. Anatomical studies reveal that these filaments, present in all adult polynemids, exhibit distinct segmentation and thickness compared to standard fin rays, enabling sensory detection of prey through taste buds and mechanoreceptors. This adaptation likely arose post-Paleogene, coinciding with the family's shift toward demersal lifestyles in turbid estuarine and coastal zones.^[16]

Morphology and physiology

Physical characteristics

Threadfins exhibit an elongated, laterally compressed body covered with small to large ctenoid scales, providing a streamlined form adapted for coastal and estuarine environments.^[18] Body sizes vary significantly across the family Polynemidae, ranging from approximately 20 cm in smaller species like certain Polydactylus to over 2 m in total length for the largest, such as Eleutheronema tetradactylum, which commonly reaches 45–50 cm but can attain a maximum of 200 cm.^[19]^[20] The pectoral fins are a defining morphological feature, divided into an upper portion with 12–19 soft, membrane-bound rays and a lower portion comprising 3–16 independent, elongated filamentous rays, or "threads," that extend freely from the fin base.^[21]^[18] These threads, supported by specialized skeletal elements like pectoral radial 4, can reach lengths up to three times the body length in extreme cases, such as Polynemus kapuasensis, and serve a tactile sensory role in probing substrates.^[21] Additional traits include a terminal mouth with a projecting snout, small villiform teeth on the jaws and sometimes palatines, a forked or deeply lunate caudal fin, and a lateral line system that continues onto the caudal fin lobes.^[18]^[19] Coloration among threadfins is typically silvery, golden, or light brownish, often accented by a dark blotch at the pectoral fin base, dusky stripes along the body, or species-specific markings like orange pelvic and anal fins in Eleutheronema tetradactylum.^[18]^[19] Sexual dimorphism manifests in body proportions and size; for instance, female Polynemus paradiseus display wider dorsal-abdominal regions compared to the slimmer males, while in Eleutheronema tetradactylum, females grow larger, averaging 44.7 cm total length versus 28.9 cm for males.^[22]^[23] Growth follows the von Bertalanffy model, with lifespans estimated at 10–15 years in species like Galeoides decadactylus.^[24]

Sensory adaptations

Threadfins possess specialized pectoral filaments that serve as primary tactile sensory organs, enabling precise detection of prey and environmental cues in turbid or low-visibility conditions typical of their coastal and estuarine habitats. These elongated, free rays—numbering from 3 to 16 per pectoral fin depending on the species—extend independently from the fin membrane and are richly innervated by branches of the second spinal nerve (SV2) and the radiale laterale accessorius-occipitalis posterior (RLA-OP) nerve complex, which provide dense sensory feedback through mechanoreceptors and nerve endings at their tips. The filaments function as probes, allowing threadfins to sweep the substrate in muddy or silty waters to locate buried invertebrates and small fish without relying on vision, a adaptation particularly evident in species like Eleutheronema tetradactylum where the rays actively explore the benthos during foraging.^[21] In addition to tactile sensitivity, the pectoral filaments exhibit gustatory capabilities, with taste buds embedded along their length that connect to the RLA-OP innervation, permitting chemical detection of potential food items in contact with the rays. This dual tactile-gustatory system enhances foraging efficiency in opaque environments where visual cues are limited, representing an evolutionary specialization unique to the Polynemidae family. Anatomical studies reveal that the filaments' musculature is divided into distinct segments (segmentum radii and fili), supporting fine motor control for independent movement and sensory exploration.^[21] Threadfins also feature visual adaptations suited to dim or low-light conditions prevalent in their habitats, including relatively large eyes (eye diameter 3.0 to 3.8 times in head length) in many species, which facilitate better light capture in estuarine and coastal waters during crepuscular periods or in suspended sediment.^[18] While specific retinal modifications are not extensively documented, the eye size correlates with enhanced sensitivity to available light, aiding navigation and prey detection in variable illumination. Olfactory adaptations remain less studied, but the species' reliance on chemosensory cues in complex estuarine environments suggests a functional role in locating food and mates amid fluctuating salinities. Many threadfin species are euryhaline, exhibiting robust osmoregulatory adaptations that allow tolerance of salinities from near-freshwater (as low as 0 ppt) to full seawater (35 ppt or higher), facilitated by specialized gill ionocytes and intestinal absorption mechanisms that maintain ionic balance during migrations between riverine and marine zones. For instance, in the fourfinger threadfin (Eleutheronema tetradactylum), optimal growth and survival occur across a broad salinity gradient (5–30 ppt), with metabolic adjustments minimizing energy costs for ion transport under hypo- or hyperosmotic stress. These physiological tolerances indirectly support sensory functions by enabling habitation in diverse, often turbid habitats where other senses predominate.^[25]^[18]

Ecology

Distribution and habitat

Threadfins of the family Polynemidae are primarily distributed across tropical and subtropical waters of the Indo-West Pacific, ranging from East Africa and the western Indian Ocean to Southeast Asia, Oceania, and northern Australia.^[26] This vast region includes coastal areas from the Persian Gulf eastward to Papua New Guinea and oceanic islands, with significant concentrations in South Asia and the Middle East.^[26] A smaller number of species occur in the Atlantic Ocean, notably in West Africa and the western Atlantic (e.g., Polydactylus octonemus from the Gulf of Mexico to Brazil), while two species (Polydactylus opercularis and P. approximans) are endemic to the eastern Pacific from California to Peru.^[27] The family is notably absent from temperate and polar seas. These fish prefer coastal marine and brackish environments, including estuaries, mangroves, lagoons, and river mouths, typically over sandy or muddy substrates.^[26] They occupy shallow waters from the intertidal zone to depths of about 50 m, though some venture to 100 m or more offshore.^[26] Threadfins thrive in tropical and subtropical conditions with water temperatures ranging from 20°C to 30°C, reflecting their adaptation to warm, stable climates. Many threadfin species are euryhaline, tolerating a broad salinity range of 0 to 35 ppt, which enables them to inhabit both fully marine and low-salinity estuarine or even freshwater systems.^[26] Their habitats are often dynamic, influenced by tidal fluctuations that affect water flow and prey availability in coastal zones.^[28] In Indo-Pacific regions, seasonal monsoons play a key role by altering salinity, nutrient influx, and habitat accessibility through increased river discharge.^[29] Some threadfin species exhibit catadromous migration patterns, where juveniles enter freshwater or estuarine habitats for growth before adults return to marine waters for spawning.^[30] Specific ranges for individual genera and species align within these broader distributional patterns.^[26]

Reproduction and life cycle

Threadfins in the family Polynemidae are predominantly oviparous, employing external fertilization where females release buoyant, pelagic eggs into the water column during spawning, which are then fertilized by males. This reproductive mode is characteristic across the family, with eggs developing as part of the planktonic community until hatching.^[12] Spawning typically occurs seasonally in tropical and subtropical regions, often linked to monsoon periods that enhance larval dispersal and survival; for instance, in species like Eleutheronema tetradactylum, peak spawning aligns with post-monsoon months such as September-October in coastal shallows and estuaries of the Arabian Sea.^[31] These events involve batch spawning, where females produce multiple clutches over an extended period, with fecundity ranging from approximately 180,000 to 1.23 million eggs per individual, varying by species and environmental conditions.^[31] In Polynemus paradiseus, for example, fecundity peaks at around 32,000 to 42,000 ova during major spawning pulses in June.^[32] The life cycle begins with these pelagic eggs hatching into planktonic larvae, which resemble elongated, transparent forms adapted for drift in coastal currents, lasting about 13 days post-hatching in E. tetradactylum. Larvae then undergo settlement around 15-20 days after hatching, transitioning to demersal juveniles that seek protected nursery habitats such as mangroves and brackish estuaries for growth and refuge from predators. Juveniles exhibit rapid initial growth, influenced by water temperature—species like threadfins show intolerance to temperatures below 14°C and prefer warmer conditions above 23°C for optimal development—before maturing into adults. Sexual maturation generally occurs at 1-3 years of age, with many species reaching reproductive readiness by 2-3 years; for E. tetradactylum, females mature at 25-30 cm total length and males at 20-25 cm.^[12]^[31] Sex ratios in threadfin populations are typically balanced at approximately 1:1, supporting effective fertilization during spawning aggregations.^[31] Hermaphroditism is rare within the family, though some species, such as E. tetradactylum, exhibit protandrous patterns where individuals transition from male to female functionality later in life. Overall, the life cycle emphasizes high fecundity and dispersive larval phases to colonize varied coastal environments, with growth rates decelerating after the juvenile stage as individuals reach sizes up to 1 meter or more in larger species.^[12]

Diet and feeding behavior

Threadfins, belonging to the family Polynemidae, are opportunistic carnivores that primarily consume benthic invertebrates, including crustaceans such as penaeid shrimps and crabs, polychaete worms, and small teleost fishes.^[33]^[34] Their diet reflects adaptation to estuarine and coastal habitats, where they forage on abundant demersal prey, with variations across species and regions; for instance, in Eleutheronema tetradactylum from Thai waters, penaeid shrimps accounted for 50.2% and teleost fishes for 33.3% of the diet by index of relative importance.^[33] In Pacific threadfin (Polydactylus sexfilis), crustaceans dominate, comprising the bulk of prey items alongside polychaetes.^[34] Feeding mechanisms involve the elongated pectoral fin filaments, which function as tactile and gustatory sensors to probe sediments and detect hidden prey like buried prawns, crabs, and worms by vibrations and chemical cues.^[21]^[7] These filaments enable precise exploration of muddy or sandy bottoms, enhancing prey detection in turbid environments. Stomach content analyses across species confirm high reliance on crustaceans, often exceeding 70% by volume or frequency in juveniles and small adults of E. tetradactylum, where penaeid shrimps alone reached 71.3%.^[33] Threadfins exhibit heightened activity during tidal transitions, particularly slack water, when prey is more accessible in shallow margins.^[7] As mid-level predators with trophic levels around 3.0–3.7, threadfins occupy a key position in coastal food webs, facilitating energy transfer from lower trophic tiers.^[33] Ontogenetic diet shifts are pronounced: juveniles primarily ingest planktonic items like Acetes shrimp postlarvae (up to 69.5% in E. tetradactylum), transitioning to larger benthic crustaceans and fishes as mouth size increases with growth, allowing consumption of prey up to 88% of gape width.^[33]^[34] In P. sexfilis, larger individuals shift toward crabs and fish, reducing intake of smaller amphipods.^[34] Ecologically, threadfins influence community dynamics by preying on commercially significant species, such as penaeid shrimps and clupeiform fishes, which form shared diet components with co-occurring predators.^[33] High trophic overlap (Schoener's index >0.60) with species like Epinephelus coioides and Lutjanus russelli underscores competition for resources in shared habitats, potentially shaping demersal fish assemblages.^[33] This predatory role supports biodiversity by controlling invertebrate populations but also positions threadfins as intermediaries vulnerable to perturbations in lower trophic levels.^[33]

Human interactions

Culinary uses

Threadfins, particularly species like the fourfinger threadfin (Eleutheronema tetradactylum), are valued in Southeast Asian cuisines for their firm, mild-flavored flesh, often prepared fresh to highlight natural tastes. In Hong Kong and Cantonese cooking, steaming is a preferred method, as seen in dishes like steamed threadfin with chicken oil, Shaoxing wine, or salted pork and preserved vegetables, which preserve the fish's delicate texture and subtle sweetness. Malaysian and Singaporean traditions feature ikan kurau (the local name for E. tetradactylum) in pan-fried preparations with salted radish or braised with basil leaves, emphasizing its suitability for simple, flavorful home cooking. In Thai cuisine, threadfin is grilled or incorporated into spicy curries, contributing to regional seafood staples that balance tenderness with a non-fishy profile.^[35]^[36] Across Pacific Islander and broader Asian contexts, threadfin holds commercial value as both fresh catches and dried products like salted ikan kurau, which are stir-fried or added to rice dishes for enhanced umami. The fish's seasonal availability, peaking in winter months, influences its prominence in festive or traditional meals, such as confit-style preparations in modern interpretations.^[37]^[35]^[36] Nutritionally, threadfins offer high-quality protein, approximately 18-20 g per 100 g serving, along with significant omega-3 fatty acids that support heart health and cognitive development. As small to medium-sized coastal fish, threadfins generally have low mercury concentrations, well below risk thresholds for regular consumption. Preparation methods like steaming or low-heat pan-frying retain these nutrients better than deep-frying, which can alter fatty acid profiles, while drying or smoking extends shelf life for preserved uses without compromising core benefits.^[37]

Aquaculture and mariculture

Threadfin species, particularly the fourfinger threadfin (Eleutheronema tetradactylum) and Pacific threadfin (Polydactylus sexfilis), are increasingly cultivated through aquaculture and mariculture practices in Asia and the Pacific to meet demand amid declining wild stocks.^[38]^[39] These efforts focus on coastal and brackishwater systems, with cultivation expanding since the 1990s to support food security and export markets.^[40] Pond-based mariculture predominates for E. tetradactylum in countries like Vietnam, India, and Taiwan, utilizing brackishwater ponds in coastal zones and repurposed abandoned shrimp farms.^[38]^[41] In Vietnam, certified processes for fingerling breeding and commercial pond farming were established in 2019, enabling cultivation in degraded shrimp areas to diversify production.^[38] Cage culture is employed for P. sexfilis in offshore or coastal settings, such as submerged sea cages in Hawaii, where juveniles are transferred via pipes and grown in volumes up to 3,000 m³.^[39] Polyculture systems show promise, particularly in India, where E. tetradactylum is integrated into abandoned shrimp ponds either in monoculture or alongside compatible species to optimize resource use.^[41] Cultivation relies on larval rearing from wild-caught or artificially induced broodstock, with newly hatched E. tetradactylum larvae (1.3 mm total length) reared in indoor cement tanks under natural light and flow-through conditions (temperature 24–31°C, salinity 33–37 psu).^[42] Initial feeding involves rotifers (150–250 μm) and copepods (110–1,000 μm) from 4 days post-hatching, supporting growth to 38 mm by 41 days.^[42] Nursery phases use high stocking densities up to 2,000 fish/m³ in 20 L tanks with 100% hourly water exchange, achieving 62% survival over 30 days on floating high-protein feeds (46% protein).^[42] Growout feeds emphasize commercial pellets optimized for 50% protein and 12% lipid content, with feed conversion ratios of 1.3–1.5; P. sexfilis juveniles transition from 2.5 mm to 5 mm pellets fed 2–3 times daily.^[39] Market size (0.5–1 kg) is reached in 6–12 months, depending on species and conditions, though high mortality from digestive issues persists in regions like Vietnam without specialized feeds.^[39]^[38] Economically, threadfin aquaculture holds significant value due to premium pricing and export potential, with E. tetradactylum fetching US$10–12 per kg in Asian markets, particularly for exports to China.^[38] In Taiwan, production is concentrated in southern counties like Pingtung, where feed costs dominate expenses but improved management boosts profitability through higher survival rates.^[40] For P. sexfilis, off-farm prices range from US$8.80–13.20 per kg, supporting feasibility in offshore systems despite challenges like fry quality.^[39] Overall production remains limited and emerging, with Vietnam scaling fingerling output via broodstock facilities and India exploring pond conversions for higher yields.^[38]^[41]

Conservation and threats

Threadfin species within the family Polynemidae exhibit varied conservation statuses according to the IUCN Red List, with many classified as Least Concern or not evaluated due to their wide distributions and lack of comprehensive assessments, while others face heightened risks from regional pressures.^[43]^[44] For instance, the fourfinger threadfin (Eleutheronema tetradactylum) has not been globally evaluated by the IUCN but is assessed as Endangered in regional contexts, such as the Indo-West Pacific, primarily owing to overexploitation in Southeast Asian waters where it supports substantial commercial fisheries.^[6] Similarly, the paradise threadfin (Polynemus paradiseus) is assessed as Least Concern (2018), reflecting stable populations in parts of its Indo-West Pacific range.^[44] The primary threats to threadfin populations stem from overfishing, particularly through trawling operations that result in high bycatch rates of juveniles and subadults, exacerbating stock depletions in tropical coastal fisheries.^[45] Habitat loss due to mangrove deforestation, driven by aquaculture expansion and coastal development, disrupts essential nursery grounds where threadfin larvae and juveniles seek shelter and forage, leading to reduced recruitment success.^[46] Climate change compounds these issues by altering sea surface temperatures, which influence spawning cues; threadfins typically spawn at optimal temperatures of 28–29°C, and shifts beyond this range can delay or desynchronize reproduction, potentially lowering larval survival rates.^[47]^[48] Management efforts include fisheries regulations such as minimum size limits in Australia, where king threadfin (Polydactylus macrochir) faces a 65 cm limit on the Queensland east coast to protect breeding adults, alongside bag limits of five per person to curb recreational harvest.^[49]^[50] In the broader Indo-Pacific, marine protected areas (MPAs) provide refuges that enhance threadfin biomass by restricting fishing in critical habitats, as demonstrated in regional networks supporting population recovery.^[51] Stock assessments reveal declines of 30–50% or more in some areas since 2000, such as in the Gulf of Carpentaria where king threadfin biomass has fallen to 13–44% of unfished levels (as of 2023) due to sustained fishing pressure.^[52] Ongoing research gaps highlight the need for genetic monitoring to delineate stock structures and track connectivity across Indo-Pacific populations, enabling more targeted conservation amid exploitation. Efforts to reduce bycatch in trawl fisheries remain underdeveloped for threadfins, with calls for improved gear technologies and observer programs to quantify and mitigate incidental captures. Threadfins play a key role in mangrove food webs as predators of invertebrates and small fish, contributing to ecosystem services like nutrient cycling and biodiversity maintenance, which underscores the urgency of integrated habitat protections.^[53]

References

[1]
Family : Polynemidae - Digital Fish Library
Habitat: Coastal waters, river mouths and estuaries, generally over sand or mud bottoms. Remarks: The common name "Threadfins" derives from their odd ...
[2]
FAMILY Details for Polynemidae - Threadfins - FishBase
Nov 29, 2012 · FAMILY Details for Polynemidae - Threadfins. Chiefly marine and brackish. Some riverine.Missing: habitat | Show results with:habitat
[3]
POLYNEMIDAE, Threadfins, Bobos - Shorefishes - The Fishes - Taxa
The family is worldwide and contains about 40 species in 8 genera, occurring in all tropical and subtropical seas. Only two endemic species from one genus are ...
[4]
[PDF] The family Polynemidae comprises 41 species in 8
(6) Habitat and Biology: Information on habitat, feeding preferences, reproduction and behaviour is given. (7) Size: The maximum known size for each species ...
[5]
Getting to Know Threadfin Fish: Characteristics, Habitat, and Behavior
May 14, 2025 · This fish has high economic value and is often consumed in Southeast Asia, including Indonesia.
[6]
Diversity of life history and population connectivity of threadfin fish ...
Mar 9, 2023 · Estuaries are important nursery areas for numerous fishes with highly dynamic habitats ... Threadfins of the World (family Polynemidae). An ...
[7]
[PDF] THREADFINS - Marine Waters
Where there was sufficient distances or bio-geographical barriers such as headlands separating adjacent stocks, king threadfin were also genetically distinct.
[8]
World Register of Marine Species - Polynemidae Rafinesque, 1815
Polynemidae Rafinesque, 1815 · Biota · Animalia (Kingdom) · Chordata (Phylum) · Vertebrata (Subphylum) · Gnathostomata (Infraphylum) · Osteichthyes (Parvphylum) ...
[9]
Threadfins of the World (Family Polynemidae). An annotated and ...
The present volume on the family Polynemidae includes 41 species belonging to 8 genera. There is an introductory section with general remarks on habitat and ...
[10]
Phylogenetic classification of bony fishes | BMC Ecology and Evolution
Jul 6, 2017 · The updated classification presented here is based on phylogenies inferred using molecular and genomic data for nearly 2000 fishes.
[11]
Anatomy and evolution of the pectoral filaments of threadfins ...
Oct 20, 2020 · The most remarkable anatomical specialization of threadfins (Percomorphacea: Polynemidae) is the division of their pectoral fin into an ...<|control11|><|separator|>
[12]
[PDF] THREADFINS OF THE WORLD
The present volume on the family Polynemidae includes 41 species belonging to 8 genera. There is an introductory section with general remarks on habitat and ...
[13]
Unlocking the genomic potential of historical and formalin-fixed ...
Sep 30, 2025 · Polynemidae, Polydactylus opercularis, Modern DNA, 8.353, 50.1 ; Polynemidae, “Polydactylus” quadrifilis, Modern DNA, 9.83, 49.2 ...
[14]
(PDF) Stock assessment of fourfinger threadfin (Eleutheronema ...
Jul 26, 2024 · The IUCN Red List of Threatened Species (Motomura et al 2015) issues the threat level for this species into the endangered category.
[15]
https://doi.org/10.3390/genes16010088
[16]
https://doi.org/10.1038/s41598-020-74896-y
[17]
https://doi.org/10.1111/jfb.14997
[18]
[PDF] POLYN 1983 FAO SPECIES IDENTIFICATION SHEETS FISHING ...
All other polynemid species: have 4, 6 or 7 free pectoral filamentous rays (5 in P. indicus). SIZE: Maximum: 142 cm; common to 80 cm. GEOGRAPHICAL DISTRIBUTION ...
[19]
[PDF] FAO SPECIES IDENTIFICATION SHEETS POLYNEMIDAE ...
Eleutheronema. Polynemus lower lip. Page 4. SIZE: Maximum: 200 cm; common: 45 to 50 cm. GEOGRAPHICAL DISTRIBUTION AND BEHAVIOUR: Throughout northern part of ...
[20]
Genome of the four-finger threadfin Eleutheronema tetradactylum ...
Oct 19, 2020 · E. tetradactylum is a particularly valued species, not least because of its large size compared to other threadfins (~ 2 m maximum length).
[21]
Anatomy and evolution of the pectoral filaments of threadfins ... - NIH
Oct 20, 2020 · Whereas most percomorphs typically have four or five muscles serving the pectoral fin, adult polynemids have up to 11 independent divisions in ...
[22]
Body shape divergence of paradise thread fish (Polynemus ...
Traits that enhance mating success, such as body size or fin morphology, could be under selective pressure, leading to the observed pronounced sexual ...
[23]
None
### Summary of Sexual Dimorphism in Eleutheronema tetradactylum
[24]
Growth, Mortality and Exploitation rates of Lesser African threadfin ...
Von Bertalanffy parameters were estimated at asymptotic length (L∞) = 54.08 cm, growth rate (K) = 0.19 per year, the longevity (Tmax) = 15.8 years, theoretical ...
[25]
Effects of salinity on growth, survival, tissue structure ... - Frontiers
Osmoregulation is an energy-intensive process in fish, and metabolic indicators can provide insight into the metabolic status of fish under different salinity ...
[26]
https://www.fao.org/3/y5398e/y5398e00.htm
[27]
[PDF] polynemidae.pdf - California Academy of Sciences
Threadfins are epibenthic perciform fishes of shallow tropical and subtropical, primarily marine, waters. They are mostly dull silvery or brownish, ...
[28]
[PDF] The Polynemid Fishes of India BULLETIN No. 18 CENTRAL ...
The family Polynemidae is classified by Day under Polynemiformes of the order Acanthopterygii; ... Studies on the life-history and feeding habits of the threadfin ...
[29]
Seasonal Variations of Growth Pattern and Condition of Paradise ...
Aug 6, 2025 · Seasonal Variations of Growth Pattern and Condition of Paradise threadfin Polynemus paradiseus (Polynemidae) from Tetulia River in Southern ...
[30]
A baseline for biodiversity: spatio-temporal variability of fish ...
Sep 1, 2025 · Polynemidae ... Marine and estuarine opportunist species dominate in higher salinity zones, while freshwater and catadromous species are more ...
[31]
Reproductive biology of fourfinger threadfin, Eleutheronema ...
Jun 30, 2025 · tetradactylum is a multiple spawner with asynchronous ovary having prolonged spawning season from March to November with a peak during August to ...<|control11|><|separator|>
[32]
Reproductive biology of paradise threadfin Polynemus paradiseus ...
This study suggested that, P. paradiseus has a distinct yearly reproductive cycle and an extended spawning season with two annual peaks. The current study of ...
[33]
Feeding habits of four-finger threadfin fish, Eleutheronema ... - NIH
Jan 30, 2023 · Average standard lengths for male, female and transitional sex fishes used for this study were 19.04 ± 8.13 cm, 29.75 ± 5.04 and 29.21 ± 2.28 cm ...
[34]
Feeding Habits of Wild and Hatchery-Reared Pacific Threadfin ...
The diets of both were primarily composed of crustaceans and strongly overlapped (> 0.80). Relative prey weights did not differ significantly between cultured ...
[35]
Threadfin: The hottest old-new fish - MICHELIN Guide
Feb 27, 2023 · ... Eleutheronema tetradactylum) and East Asian Fourfinger Threadfin (Eleutheronema rhadinum). ... The silky and boneless centre cuts are used in ...
[36]
What is threadfin? 'Almost like salmon, but without the bad rep,' say ...
Jun 20, 2022 · Threadfin, a type of oily fish, is a popular seafood option in many Hong Kong restaurants. Chefs explain why they put it on their menus · Company.
[37]
[PDF] Small fish for food security and nutrition - FAO Knowledge Repository
The 100 Indian rupees she has available today buys her a few threadfin bream (Nemipterus spp.; Tamil: sankara) with which she can prepare a tasty fish curry.
[38]
[PDF] Fatty acid composition analyses of commercially important fish ...
Jan 30, 2020 · This study investigated the lipid contents, fatty acid compositions, and nutritional qualities of 22 commercially important marine fish species ...
[39]
http://www.ctsa.org/files/publications/CTSA_1456316728542774482721.pdf
[40]
Amberjack and fourfinger threadfin open new avenues for marine ...
Vietnam is making significant strides in marine aquaculture diversification with two native fish species, amberjack (Seriola dumerili) and fourfinger threadfin ...
[41]
[PDF] Growout Techniques for the Pacific Threadfin Polydactylus sexfilis
Offshore cage culture: culture system using floating or submersible cages or net pens away from near shore or coastal habitat. Cages may vary in shape and sizes ...
[42]
Bioeconomic evaluation of Eleutheronema tetradactylum farming
Aug 7, 2025 · Eleutheronema tetradactylum is a recently developed product in aquaculture systems in Taiwan. Its production is concentrated in the Pingtung ...
[43]
Growth and Survival of Indian Salmon Eleutheronema tetradactylum ...
Apr 4, 2011 · This study was conducted to assess the growth performance and survival rate of a commercially important finfish Eleutheronema tetradactylum in 100 m -2 of ...
[44]
Larval and juvenile development and the effects of stocking density ...
Sep 14, 2022 · Larval and juvenile development and the effects of stocking density on the nursery performance of fourfinger threadfin (Eleutheronema ...
[45]
https://bioflux.com.ro/docs/2024.1143-1150.pdf
[46]
Polydactylus nigripinnis, Blackfin threadfin - FishBase
Pectoral fin rays unbranched, blackish; tip of uppermost filament reaching to or just short of level of posterior tip of upper part of pectoral fin (Ref. 41110) ...Missing: definition | Show results with:definition
[47]
Estimating the total allowable catch and management of Threadfin ...
Therefore, a "dual control" system that limits the total number and engine power of fishing vessels has been used to alleviate increased fish stock declines ( ...
[48]
[PDF] Stock assessment of fourfinger threadfin (Eleutheronema ... - Bioflux
Jun 27, 2024 · The results of the analysis showed that the fish growth pattern was allometric negative in three locations, namely Tanjung Balai, Bagan Serdang, ...Missing: aquaculture | Show results with:aquaculture
[49]
Impact of mangrove forests degradation on biodiversity and ... - Nature
Sep 5, 2018 · We report here that disturbed mangrove area showed a loss of 20% of benthic biodiversity, with the local extinction of four Phyla (Cladocera, ...Missing: threadfin | Show results with:threadfin
[50]
[PDF] Impact of rise in seawater temperature on the spawning of threadf1n ...
Fish have strong temperature preferences to spawning. Several species of marine fish are known to spawn only at favorable water temperature that is known to ...
[51]
Assessing the sustainability of threadfin bream fishery along South ...
In contrast, deviations in Sea Surface Temperature, Sea Surface Salinity, ocean isothermal layer depth, and surface currents revealed adverse effects surpassing ...
[52]
[PDF] Threadfin salmon - GBRMPA eLibrary
under the East Coast Inshore Fin Fish Fishery, a minimum size limit of 60 cm for king threadfin and. 40 cm for blue threadfin; recreational bag limit of five.
[53]
Size and possession limits in tidal waters | Recreation, sport and arts
Aug 19, 2025 · Threadfin (salmon) ; King threadfin on the Queensland east coast. 65cm min. Limit of 5 ; King threadfin in the Gulf of Carpentaria. 60cm min
[54]
The application of genetics to marine management and conservation
Aug 9, 2025 · We discuss the application of genetic data to the design and evaluation of the effectiveness of marine protected area networks, stock ...
[55]
[PDF] Genetic Diversity Analysis of Indian Salmon, Eleutheronema ...
Dec 14, 2015 · Eleutheronema tetradactylum is an important commercial fish species exposed to intense exploitation both in Southeast Asian countries.