Aprionodon acutidens queenslandicus Whitley, 1939 Carcharias acutidens Rüppell, 1837 Carcharias forskalii* Klunzinger, 1871 Carcharias munzingeri Kossmann & Räuber, 1877 Eulamia odontaspis Fowler, 1908 Hemigaleops fosteri Schultz & Welander, 1953 Mystidens innominatus Whitley, 1944 Negaprion queenslandicus Whitley, 1939 Odontaspis madagascariensis Fourmanoir, 1961 * ambiguous synonym The sicklefin lemon shark (Negaprion acutidens) or sharptooth lemon shark is a species of requiem shark belonging to the family Carcharhinidae, widely distributed in the tropical waters of the Indo-Pacific.

A slow-moving predator feeding mainly on bony fishes, the sicklefin lemon shark seldom travels long distances and many individuals can be found year-round at certain locations.

Although they are potentially dangerous to humans and known to respond vigorously to any provocation, under normal circumstances, sicklefin lemon sharks are cautious and tend to retreat if approached.

The IUCN has assessed this species as Endangered; its low reproductive productivity and rate of movement limits the capacity of depleted stocks to recover.

Off India and Southeast Asia, this species has been severely depleted or extirpated by unregulated exploitation for its meat, fins, and liver oil.

The sicklefin lemon shark was first described as Carcharias acutidens by German naturalist Eduard Rüppell, in the 1837 Fische des Rothen Meeres (Fishes of the Red Sea).

Significant levels of genetic differentiation between sicklefin lemon sharks in Australia and French Polynesia, 7,500 km (4,700 mi) apart, suggest that little intermingling occurs between regional subpopulations.

[11] Another study at Moorea in French Polynesia found that some of the local sharks were year-round residents of the island, while others were more transitory and visited only occasionally.

[12] Over 90% of the sicklefin lemon shark's diet consists of bottom- and shore-dwelling teleosts, including herring, mullets, mackerel, silversides, needlefish, smelt-whitings, porgies, sea catfish, triggerfish, parrotfish, and porcupinefish.

[19] As with other members of its family, the sicklefin lemon shark is viviparous; the developing embryos are sustained by a placental connection formed from their depleted yolk sacs.

[4] Parturition occurs in October or November at Madagascar and Aldabra, and in January at French Polynesia; ovulation and mating for nonpregnant females takes place at around the same time.

Due to its formidable size and teeth, it is regarded as potentially dangerous, and certainly this species has been known to defend itself quickly and vigorously if touched, speared, or otherwise provoked or alarmed.

[3] The IUCN has assessed the sicklefin lemon shark globally as Endangered; it is harvested using anchored and floating gillnets, beach nets, and longlines.

Widespread habitat degradation, including pollution and blast fishing on coral reefs and deforestation in mangroves, poses an additional threat to the survival of this species in the region.

Already, the sicklefin lemon shark has been extirpated in parts of India and Thailand, and has not been reported from Indonesian markets in recent years despite being historically abundant there.