The Ceylon killifish (; ''Aplocheilus dayi'') 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), ...

killifish A killifish is any of various oviparous (egg-laying) cyprinodontiform fish, including families Aplocheilidae, Pantanodontidae, Cyprinodontidae, Fundulidae, Nothobranchiidae, Profundulidae, Aphaniidae and Valenciidae. All together, there ar ...

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 ...

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

. It grows to a length of . Males and females have a black dot at the rear end of the base of the

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 ...

. Females lay 50–150 eggs. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

of this fish honours the Inspector-General of Fisheries in India

Francis Day Francis Talbot Day (2 March 1829 – 10 July 1889) was an army surgeon and naturalist in the Madras Presidency who later became the Inspector-General of Fisheries in British Raj, India and British rule in Burma, Burma. A pioneer ichthyologist, ...

(1829–1889), who first reported this fish, although he identified it as ''

Aplocheilus panchax The blue panchax or whitespot (''Aplocheilus panchax'') is a common freshwater fish found in a large variety of habitats due to its high adaptability. This species is native to southern Asia from Pakistan, India to Indonesia. It has been discover ...

''.

References

Tropical fish Taxa named by Franz Steindachner Fish described in 1892 Ceylon killifish Freshwater fish of Sri Lanka {{Cyprinodontiformes-stub