Sri Lanka (5–9°80'N; 79°84'-82°E), an island of approximately 65,000 km2, is relatively small for a continental island. In spite of the maritime influence on the island from time immemorial, with a coast line of 1760 km, the island is reputed to possess at present 3 ha of inland lentic water for every km2 of the island (De Silva, 1983). This perhaps is the highest density of inland water available for any island in the world. Uniquely, all this vast hectarage of water is created by man, spanning nearly a period of 2000 years. It is not suprising, therefore, that the man-made lakes, or the reservoirs, have played a determining role in shaping the life pattern of the people of this relatively small continental island; the reservoirs of Sri Lanka have been a part and parcel of the civilization of a complete race - the Sinhalese, reputed for their irrigation marvels. It is equally not surprising that references to these facts are depicted not only in the history of the race, but also in modern folklore, songs etc.
It is well documented that the oldest known human civilizations originated in the valleys of major rivers, such as the Euphrates. In the Indian sub-continent the major civilizations evolved in the valleys of the Indus, Ganges, Yamuna etc. In Sri Lanka, formerly known as Ceylon or Lanka, the parallel is not that clear cut. By virtue of the nature of its terrain this continental island did not possess rivers of the magnitude of its continental neighbour; there were no great valleys to speak of. In such a context the civilizations developed and thrived as a result of the ingenuity of man himself who made improvisations for the effective utilization of meagre gifts of nature, in particular the effective utilization of the seasonal and limited rainfall. Therefore, apart from the Buddhistic traditions, if one were to single out another factor underlying the civilization of the Sinhala race, it is undoubtedly the creation of the reservoirs, and the near perfection of associated water management technology.
In view of the importance of reservoirs in the lives of the people it is not surprising that much has been written on them. The historical aspects have been dealt with by Brohier (1934,1937), De Camp (1974), Fernando,A.D.N. (1979) and Parker (1981); sociological impact of reservoirs by Ellepola (1955), Brohier (1937) and Perera (1984); the engineering aspects by Brohier (1934, 1937), Van de Lippe (1951), Schnitter (1967), Smith (1971), De Camp (1974), the limnological and biological aspects by a host of authors, as reviewed by Fernando and De Silva (1984). Aspects of the fisheries of reservoirs have been dealt with in general terms by Fernando and Indrasena (1969), Mendis (1965, 1977), Fernando (1977,1980), De Silva (1983), and Fernando and De Silva (1984), and the fisheries of individual reservoirs or the biology of constituent species by a number of authors (De Silva and Fernando, 1980; De Silva, 1985a; Schiemer, 1983; De Silva, 1986; and some others).
Almost all studies on the utilization of reservoirs for fishery purposes have been done predominantly on the major reservoirs, with a few exceptions (Mendis, 1965; Fernando and Ellepola, 1969; Thayaparan, 1982). The village or the seasonal tanks which greatly surpass the major reservoirs in number and which constitute nearly 33% of the total reservoir surface area have received little attention. The socio-economic aspects of the reservoir fishery have been totally neglected.
The present study reviews the role of reservoirs in fish production, i.e. all aspects relating to the reservoir fishery based on present knowledge with the view of highlighting possible strategies for its sustenance and scientific management.