Needlefish

Commonly referred to as fish with pointy noses or long toms, the needlefish belong to the family Belonidae. The needlefish are piscivorous fishes and are found primarily on the surface of the sea or marine habitats that are very shallow. Additionally, some of the needlefish are also found in brackish, marine (sea needlefish) and freshwater environments. These include the genera Strongylura. On the other hand, genera such as Potamorrhaphis, Belonion and Xenentodon are found exclusively in freshwater streams and rivers. 

In this article, we will attempt to learn why the needlefish is known as the fish with pointy nose or needle nose fish and if there is the presence of any actual nose. In addition, we will also discuss the description, reproduction, habitat, etc. of the needlefish. 

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Needlefish Description 

There is a close resemblance between the needlefish and the North American gars found in freshwater that belong to the family Lepisosteidae. They resemble each other in having a slender elongated body and narrow, long jaws containing sharp teeth. This is the reason why certain species of needlefish are referred to as garfish or gars and even the needlefish Belone belone was initially called ‘garfish’. However, needlefish is only a distant relative of the true gars. 

The body of the needlefish is slender and its length ranges from 3 to 95 cm or 1.2 to 37.4 inches. 

A single dorsal fin is present on the body towards the far back, almost oppositely positioned to the anal fin. They have earned the name ‘needle nose fish’ owing to their narrow, long beak. Multiple sharp teeth are contained within this beak. The upper jaw of most of the species of needlefish reaches its full length only when they attain adulthood, giving the juveniles a half-beak appearance. The lower jaw in the juvenile needlefish is elongated but the upper jaw is much smaller. The needlefish’s perfectly streamlined body helps it in achieving high velocities while swimming. 

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Needlefish Habitat and Distribution

The needlefish family Belonidae contains various species that are widely distributed. Their habitat can vary from freshwater, brackish water to marine settings. The needlefish, most commonly, are found in the tropical waters while certain species are known to inhabit temperate waters, during the winter season in particular. Some small specimens have recently been found in the Mediterranean sea as well. Needlefish are often found swimming in schools close to the surface with males defending their territory during the process of feeding. The common North Atlantic Belone belone is often seen swimming in schools alongside tuna. 

Diet of Needlefish

Needlefish are usually seen hunting and feeding on other small fish, crustaceans and cephalopods. The species of needlefish found in saltwater are predatory in nature as well. The Indian species, in particular, is known to feed on large crustaceans exclusively. The juveniles with their underdeveloped upper jaw primarily feed on plankton.

Needlefish are known to hunt their prey quickly. They are known to take advantage of what is known as Snell’s Window when they attack their prey. As the light gets refracted through water, objects present at the window’s edges appear distorted. This allows for disruption of the needlefish’s leaping image and allows them to get within close ranges of its prey. They use their head in an upward motion and use their sharp teeth to bite the prey. 

Reproduction in Needlefish

Mating in needlefish, usually, occurs in the months of April and May. The male is known to search for the female and also engage in competition with other males in order to secure their mates. Males are larger than the females and ride atop the latter during the process of mating. Needlefishes are oviparous in nature and lay their eggs in areas of shallow waters. A majority of the needlefish are known to migrate to shallow waters for the process of spawning. Needlefish are known to produce up to 100 eggs either attached to one another or borne on a host plant. The incubation period of the eggs is 10 to 15 days, on completion of which numerous needlefish fry are hatched each around 0.5 inches in length. Interbreeding or hybrids of needlefish have not been reported so far despite there being numerous species of needlefish. 

Predators of Needlefish

Needlefish are highly prone to predation, given their slender body with weak bones and their habit of swimming in proximity to the surface. The most common predators of the needlefish include dolphins and sharks. Several birds like ospreys, hawks and eagles are also known to prey on needlefish. The population of needlefish is also affected by human fishing activities but on a lower level. 

Needlefish Taxonomy

The classification of the needlefish is within the order Beloniformes where they are placed along with the sauries of the family Scomberesocidae. Together they comprise the superfamily Scomberesocoidea. This is one of the two superfamilies of the suborder Exocoetoidei consisting of all of the Beloniformes with the exception of the ricefishes of the Adrianichthydae family. Evolutionists have concluded that the Belone genus is the sauries’ sister group. Given this is the correct assumption, Belonidae is monophyletic only in case of the inclusion of sauries within it. 

Some Important Needlefish Genera

Needlefish have a wide variety of species divided into 10 different genera which include - Belone, Ablennes, Belonion, Platybelone, Petalichthys, Potamorrhaphis, Strongylura, Tylosurus, Pseudotylosurus, and Xenentodon. Some important characteristics and behaviour of the different genera of needlefish are provided below. 

Genus Belone

This genus is known to comprise two species of needlefish.

• Belone belone 

• Belone svetovidovi

Belone belone, found in the  Atlantic Ocean, Caribbean Sea, Baltic Sea, Mediterranean Sea is commonly known as the sea needle. Adults of this species can measure up to 95 cm (37 inches) in length. The Belone svetovidovi is shorter, with lengths running from 30 to 65 cm (12 to 26 inches).

Genus Ablennes

Only one known species, the Ablennes hians has been reported from this genus. It is an ocean-dwelling needlefish. This species can attain great lengths up to 140 cm. This species is majorly found in tropical waters or waters with moderate temperatures. It is found to flourish in the Atlantic Ocean, Indian Ocean, and Western Pacific Ocean in shallow waters near estuaries and islands. They are known to inhabit these areas due to the higher number of small fishes in such waters. 

Genus Belonion

The two species of needlefish included under this genera are

• Belonion apodion 

• Belonion dibranchodon

These are small freshwater needlefish only native to tropical South America. These species of needlefish can grow up to 4.8 cm or 2 inches in length. 

Genus Platybelone

This genus comprises only one species, the Platybelone argalus, with several subspecies. The species is also known as Keeltail needlefish given the presence of keel-like flat unique structures on either side of the tail. The length of the species can range between 40 and 50 cm. This is one of the most widely distributed species of needlefish in the world. The Keeltail fish are found in the marine waters of the Indian Ocean, the Pacific Ocean, the western Atlantic Ocean and also in the Persian Gulf and the Red sea. 

The seven recognised subspecies of this genus are: 

• P. argalus annobonensis 

• P. argalus platura 

• P. argalus argalus 

• P. argalus lovii 

• P. argalus pterura 

• P. argalus trachura 

• P. argalus platyura

Genus Petalichthys

The Cape needlefish or the Petalichthys capensis is the only species included under this genus. This genus is native to the marine waters surrounding the coast of  South Africa and hence, the name. This species is distributed across the Western Indian Ocean and the Southeast Atlantic Ocean. This species can reach a length of up to 30 to 40 cm. 

Genus Potamorrhaphis

This genus includes four species, which are: 

• Potamorrhaphis eigenmanni 

• Potamorrhaphis guianensis

• Potamorrhaphis labiatus 

• Potamorrhaphis petersi

These needlefish are smaller in length attaining a maximum of 30 cm. The species of this genus are mainly found in the marine tropical waters of South America. They are also known to inhabit river basins and freshwater bodies in the Amazon rainforest.

Genus Strongylura

The species of this genus are found in saltwater, brackish water as well as freshwater. 14 species of recognised needlefish are categorised under this genus. They include: 

• Strongylura anastomella

• Strongylura exilis

• Strongylura fluviatilis

• Strongylura krefftii

• Strongylura leiura

• Strongylura hubbsi

• Strongylura incisa

• Strongylura marina

• Strongylura scapularis

• Strongylura senegalensis

• S. notata notata

• Strongylura timucu

• Strongylura urvillii

• Strongylura notata

1. S. notata forsythia (subspecies)

2. Strongylura strongylura (subspecies)

Genus Pseudotylosurus

This genus includes two species

• Pseudotylosurus angusticeps 

• Pseudotylosurus microps

These species are found along the coast of South America. 

Genus Tylosurus

There are 6 species of fish categorised under this genus with some of the species consisting of subspecies. These include:

• Tylosurus acus

1. T. a. Acus (subspecies)

2. T. a. Imperialis (subspecies)

3. T. a. Melanotus (subspecies)

4. T. a. Rafale (subspecies)

• Tylosurus choram

• Tylosurus crocodilus

1. T. c. crocodilus (subspecies)

2. T. c. fodiator (subspecies)

• Tylosurus gavialoides

• Tylosurus pacificus 

• Tylosurus punctulatus

The species are usually the larger needlefish with lengths ranging from 50 to 60 cm and occasionally reaching up to 1 m. The species of this genera are widely cosmopolitan in their distribution. 

Genus Xenentodon

This genus comprises 2 species. These two species are: 

• Xenentodon cancila 

• Xenentodon canciloides

The species under this genus are found in Asia. They are known to inhabit freshwater bodies and their populations are prone to disruption by human and other activities such as the construction of dams. 

Needlefish and Danger to Humans

All needlefish are capable of making short jumps out of the water at high speeds. The speed at which they jump out of water can range up to 60 kmph. They are often known to leap over rather than going around the decks of shallow boats as they usually swim close to the surface. At night, artificial light is seen to greatly excite this jumping activity. This has often caused night fishermen and divers across the  Pacific Ocean to be ‘attacked’ by schools of needlefish, suddenly excited and diving towards the light source at high enough speeds. 

The sharp beaks of the needlefish are capable of inflicting serious wounds that cause deep puncture and may even break off the victim’s inside in the process. In many instances, where Pacific Islander communities traditionally and primarily fish on low boats from reefs, needlefish are known to represent greater injuries even compared to sharks. 

Aquarium Needlefish

Many species of needlefish are known to inhabit brackish water and fresh water as well. The Xenentodon cancila, a freshwater needlefish native to south-east Asia, have been used as aquarium needlefish. These needlefish are delicate and are capable of growing up to 30 to 40 cm. In the aquarium environment, this needlefish prefers a large planted area with a slightly heavy current.  

In an aquarium, it is best that needlefish are kept by themselves or with other species of peaceful fish as they respond adversely even to a slight disturbance in the water current. Given that they are easily stressed, keeping needlefish in an aquarium alongside fishes swimming mid-water or with an active movement such as silver sharks or tinfoil barbs should be avoided. Their sociable nature indicates that they thrive well when kept in a small school or with peaceful species such as the loricariid catfish, peaceful cichlids, or sleeper gobies.

Fun Facts About Needlefish

• Needlefish lack a functioning stomach. The breakdown of the food consumed is instead facilitated by the secretion of an enzyme called trypsin. 

• The flesh and bones of most needlefish species are green or blue coloured. 

• Needlefish are known to swim at high speeds attaining about 60 kmph or 37 mph. They also have the habit of jumping over boats rather than swimming underneath them. 

• Although they are not harmful to humans, are, in particular, their beak can inflict serious injuries, of which two attacks have resulted in deaths in humans so far. 

Did You Know? 

Needlefish has a low market for human consumption as their green or blue coloured bones make them look unappealing for consumption by humans. This is allowing the needlefish population to thrive with no species under any threat at present.