The Ceylon killifish (si|උඩ හඳයා|translit=uda handaya; Aplocheilus dayi) is a species of killifish endemic to Sri Lanka. This species grows to a length of 9cm (04inches). Males and females have a black dot at the rear end of the base of the dorsal fin. The females lay 50–150 eggs.[1] 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.[2]