Rather common endemic fish occurs in shallow, shaded forest streams with a silt substrate. Also not uncommon in saline parts of mangrove swamps (Pethiyagoda R., 1991). Its diet consists of small insects, insect larvae and fish fry. As per Pethiyagoda Day's Killifish is more or less confined to the Kelani basin and adjacent coastal areas(Pethiyagoda R., 1991). According to the Sujan Madhuranga it is reported from Aththanagalu and Kelani basins (Maduranga H. G. S. , 2003). Later on Prasanga Wickramatilake reported it from Udugama stream, a tributary of Gin river(Wickramatilake P., 2003) and H.B.Jayaneththi & H.G.S.Maduranga from upper tributaries of Kalu river in Kukulugala proposed forest reserve (Jayaneththi H.B. & Maduranga H.G.S, 2004). Sampath de Alvis Gunathilake noted that it is common in both Kelani and Kalu drainage (Gunathilake S. ,2007). So according to all publish data it is common from Aththanagalu basin to Gin river basin in wet zone up to lower hills.
* Male fish photographed above from unnamed stream, an upper tributary of Kalu river has unusual vertical black bar instead of usual few small spots (Usually three spots situated triangularly)
Maduranga H. G. S. (2003) සිරිලක ආවේනික මිරිදිය මසුන් (Sirilaka awenika miridiya masun). National zoological department.
Pethiyagoda, R., (1991) Freshwater fishes of Sri Lanka. Wildlife Heritage Trust, Colombo. xiv+362 pp.
Jayaneththi H.B. & Maduranga H.G.S. (2004), A preliminary study on the diversity of Ichthyofauna of Kukulugala proposed forest reserve, Rathnapura district. Sri Lanka Naturalist 6 (1&2)
Wickramatilake P., 2003 Freshwater fishes of the Udugama stream, Galle district, Southern Sri Lanka
Gunathilake S. (2007) ශ්රි ලංකාවේ මිරිදිය මසුන් (Sri Lankawe miridiya masun) (text in Sinhala), Biodiversity secretariat - Ministry of Environment.