''Neostethus thessa'', locally known as bolinao, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of freshwater priapium fish

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Lake Mainit Lake Mainit is the fourth largest lake in the Philippines, having a surface area of . The lake is also the deepest lake in the country with maximum depth reaching . It is located in the northeastern section of Mindanao and shared between the ...

Mindanao Mindanao ( ) is the List of islands of the Philippines, second-largest island in the Philippines, after Luzon, and List of islands by population, seventh-most populous island in the world. Located in the southern region of the archipelago, the ...

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

. It is classified as

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

by the

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological spe ...

due to its highly restricted range which is threatened by

pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

and the

introduction Introduction, The Introduction, Intro, or The Intro may refer to: General use * Introduction (music), an opening section of a piece of music * Introduction (writing), a beginning section to a book, article or essay which states its purpose and g ...

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

of fish.

Taxonomy

''Neostethus thessa'' was first described as ''Solenophallus thessa'' by the German

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

Horst Joachim Aurich Horst may refer to: Science * Horst (geology) In physical geography and geology, a horst is a raised fault block bounded by Fault (geology), normal faults. Horsts are typically found together with grabens. While a horst is lifted or remains s ...

in 1937. It is a member of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Neostethus ''Neostethus'' is a genus of fishes in the family Phallostethidae, native to freshwater and brackish habitats in southeast Asia, with the majority of the species restricted to the Philippines The Philippines, officially the Republic of ...

'' in the priapium fish

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Phallostethidae Phallostethidae, also known as priapium fish, is a family of atheriniform fish native to freshwater and brackish habitats in southeast Asia. They are small, no more than in length, with partially translucent bodies. They are found in fresh and ...

Distribution and habitat

''Neostethus thessa'' is only found in

in northeastern

in the

Description

''Neostethus thessa'' swim in schools and feed near the surface of the water. They are small fish, reaching a length of only around for males and for females. They are transparent to opaque gray in color. Like other priapium fish (and the origin of their

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

), the males are distinguished by a muscular clasping organ from modified fins found under their "chin". These are used by the males for mating with females via

internal fertilization Internal fertilization is the union of an egg and sperm cell during sexual reproduction inside the female body. Internal fertilization, unlike its counterpart, external fertilization, brings more control to the female with reproduction. For inte ...

. The females attach their eggs to surfaces by sticky filaments.

Conservation and uses

''Neostethus thessa'' is classified as

by the

. The lake it inhabits is only and is threatened by

from mining and agriculture runoffs and waste from residential areas around the lake. It is also threatened by the

of fish, including the

Nile tilapia The Nile tilapia (''Oreochromis niloticus'') is a species of tilapia, a cichlid occurring naturally in parts of Africa (such as its namesake Nile River) and the Levant, though numerous introduced populations exist outside its natural range. T ...

and the

Eurasian carp The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

. ''Neostethus thessa'' is caught for food with fine-meshed nets.

References

{{Taxonbar, from=Q2930189 thessa Fish described in 1937 Fish of the Philippines Endemic fish of the Philippines Animals described in 1937