''Stiphodon atropurpureus'', commonly referred to as the Philippine neon goby or blue neon dwarf goby, is a

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

of the

Gobiidae Gobiidae or gobies is a family (biology), family of bony fish in the order (biology), order Gobiiformes, one of the largest fish families comprising over 2,000 species in more than 200 genus, genera. Most of gobiid fish are relatively small, typ ...

family. It is native to parts of Asia, including 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 ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

and

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

Description

''S. atropurpureus'' has a

fusiform Fusiform (from Latin ''fusus'' ‘spindle’) means having a spindle (textiles), spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon (geometry), lemon-shape, but often implies a focal broadening of a ...

body. It measures between 20 and 50 millimeters. The two

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s have seven spines in the front and nine soft dorsal spines in the back. The visual characteristics are similar to other ''

Stiphodon ''Stiphodon'' is a genus of freshwater gobies. They inhabit swift, clear streams close to the sea and are found in large parts of Asia and Oceania. Many of the 36 currently recognized species have extremely restricted distributions on single isla ...

'' species with which it shares habitat, making identification difficult without detailed

anatomical Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

study or

genetic testing Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...

. Males display a spectrum of metallic lustre that range from green to blue to purple. This

iridescence Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear gradually to change colour as the angle of view or the angle of illumination changes. Iridescence is caused by wave interference of light in microstru ...

is most noticeable when the fish are engaged in behaviors such as mating displays or defending their territory. The male's first dorsal fin lacks elongation and a fibrous texture, but features a distinctive narrow red border, enhancing its visual appeal to other fish and playing a critical role during social interactions. Females are lighter in coloration compared to the males, exhibiting

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

. Typically, their bodies are white or a light pastel hue and are marked by two clear transverse lines that run across their bodies. These lines provide them with a protective advantage by reducing their visibility to predators. The developmental journey from juvenile to adulthood is marked by significant changes, particularly in coloration. Juveniles start with more muted tones, which gradually develop into the vibrant colours seen in adults. This progression is especially pronounced in males, as the intense coloration gained in adulthood plays a vital role in their social interactions and

reproductive success Reproductive success is an individual's production of offspring per breeding event or lifetime. This is not limited by the number of offspring produced by one individual, but also the reproductive success of these offspring themselves. Reproduct ...

Distribution and habitat

''S. atropurpureus'' is found in a variety of locations across Asia, including the

and

. These

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising over 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the fam ...

prefer the clear and oxygen-rich waters of faster streams, which provide not only the necessary environmental conditions for their survival, but also the substrates essential for their feeding habits. Despite the broad geographic range, the specific details of their

population dynamics Population dynamics is the type of mathematics used to model and study the size and age composition of populations as dynamical systems. Population dynamics is a branch of mathematical biology, and uses mathematical techniques such as differenti ...

are not well-documented. The challenges posed by their small size and elusive nature make comprehensive population studies difficult. Research efforts are generally localized, focusing on small-scale stream surveys, which do not provide a complete picture of their overall distribution. ''S. atropurpureus'' coexists with other species within 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 ...

, which share similar

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

s and

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

Reproductive behavior and life cycle

''S. atropurpureus'' undergoes a complex life cycle that is

amphidromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...

(including migration from fresh water to the sea, or vice versa, but not for the purpose of breeding). Adults breed in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

environments, where they lay their

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...

s. After hatching, the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e drift downstream to the

marine environment A marine habitat is a habitat that supports marine life. Marine life depends in some way on the saltwater that is in the sea (the term ''marine'' comes from the Latin ''mare'', meaning sea or ocean). A habitat is an ecological or environmen ...

, living planktonically. This marine phase is crucial as it allows the larvae to grow away from the competitive and predatory pressures of the freshwater environment. As they reach the post-larval stage, they begin their journey back to freshwater streams. This migration is significantly aided by their specialized

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

of fused

pelvic fins Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

. These fins form a suction disc that enables the young

to cling to rocks and other surfaces, helping them to swim against the current and navigate back to their natal streams. This life cycle is essential for maintaining the

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...

and resilience of their populations.

Feeding

''S. atropurpureus'' primarily feeds on

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

and

biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...

s, which they scrape from rocks using their subterminal mouths. This diet is rich in

nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

s and the availability of food sources is impacted by the water quality in the surrounding environment.

Conservation

Growing popularity of ''S. atropurpureus'' in the

aquarium trade Fishkeeping is a popular hobby, practiced by aquarists, concerned with keeping fish in a home aquarium or garden pond. It is a practice that encompasses the art of maintaining one's own aquatic ecosystem, featuring a lot of variety with various ...

has raised awareness of the species, although it has also led to increased harvesting from the wild (since there is currently no dedicated

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

for breeding ''S. atropurpureus'', all individuals in the aquarium trade are collected from the wild.) This practice puts more pressure on natural populations and can deplete local populations. Furthermore, research on their abundance and distribution remains limited, complicating efforts to monitor the species. Moreover, the species' requirement for high water quality and the requirement for

migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

to breed makes it vulnerable to human impacts such as

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

construction,

water pollution Water pollution (or aquatic pollution) is the contamination of Body of water, water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and ...

, and

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

. This species' high sensitivity to water quality and its inability to breed in polluted waters means that local populations could rapidly decline if the streams they inhabit are

contaminated Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for the physical body, natural environment, workplace, etc. Types of contamination Within the scienc ...

. Additionally, since their ability to migrate freely between freshwater and

marine environments A marine habitat is a habitat that supports marine life. Marine life depends in some way on the seawater, saltwater that is in the sea (the term ''marine'' comes from the Latin ''mare'', meaning sea or ocean). A habitat is an ecological or Na ...

can be hindered by obstacles like dams and water diversions, which disrupt natural water flow and degrade stream environments, they significantly affect the survival and

of this species. Habitat threats like

, construction projects, and

can alter the

water clarity Water clarity is a descriptive term for how deeply visible light penetrates through water. In addition to light penetration, the term water clarity is also often used to describe underwater visibility. Water clarity is one way that humans measure ...

, temperature, and the flow rate necessary for their migration and survival. ''S. atropurpureus'' is categorized as

Least Concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

(LC) by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

.Jaafar, Z. 2019. ''Stiphodon atropurpureus''.
The IUCN Red List of Threatened Species
' 2019: e.T91083121A91083139. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T91083121A91083139.en. Accessed on 03 December 2024.

References

{{Improve categories, date=November 2024 atropurpureus Taxa named by Albert William Herre Fish described in 1927