The Ceylon killifish (Sinhala: උඩ හඳයා, romanized: uda handaya; Aplocheilus dayi) is a species of killifish endemic to Sri Lanka.

It grows to a length of 9 cm (3.5 in).

[1] Males and females have a black dot at the rear end of the base of the dorsal fin.

[2] The specific name of this fish honours the Inspector-General of Fisheries in India Francis Day (1829–1889), who first reported this fish, although he identified it as Aplocheilus panchax.

This Cyprinodontiformes article is a stub.