World Journal of Zoology 8 (2): 154-158, 2013 ISSN 1817-3098 © IDOSI Publications, 2013 DOI: 10.5829/idosi.wjz.2013.8.2.66155 Corresponding Author: R. Alexandar, Department of Ecology and Environmental Sciences, Pondicherry University, Puducherry, India 605 014. E-mail: enviroalexandar@gmail.com. 154 Diversity of Fish Fauna and Their Threats in Ousteri Lake, Puducherry, India R. Alexandar and R. Siva Sankar Department of Ecology and Environmental Sciences, Pondicherry University, Puducherry, India 605 014 Abstract: The freshwater fish fauna of Ousteri Lake, Puducherry were studied for a period of two months from January to February 2011. We recorded 15 species belonging to 14 families and 17 genera. The status of fish species compared with IUCN-the International Union for Conservation of Nature species category. Though the fish fauna of Ousteri Lake is threatened by anthropogenic activities, the study proposes that it can be considered as a refuge for conservation of some endemic and threatened freshwater fishes of the Puducherry region. The efforts must be maintained to reduce anthropogenic intervention and avoiding an introduction of alien species. Key words: Fresh water wetland %Fish fauna %Wetland conservation %Eutrophication %Exotic species INTRODUCTION The fish fauna of Ousteri Lake is more threatened Fishes are one of the important elements in the eutrophication, siltation and a minor degree of pollution economy of many nations as they have been a stable item by surrounding industrial sewage and high level in the diet of many people [1]. Freshwater fishes are agricultural activities in marginal areas of lake and illegal important livelihood of poor people as it contains the fishing activities using nylon nets leads to destruction of important protein. Fishes are an integral part of freshwater various fresh water fauna. The main objective of this ecosystem. Fishes play an important role in energy flows, study was to assess the diversity of the fish species of nutrient cycling and maintaining community balances in Ousteri Lake and to identify its major threats for fresh water ecosystems [2, 3]. An estimated 126,000 suggesting the conservation of fresh water fish species. described species rely on freshwater habitats, including Puducherry (study area) is situated on the Coromandal species of fishes, molluscs, reptiles, insects, plants and Coast between 11°52'N; 79°45'E and11°59'N, 79°52'E. mammals. Freshwater fishes comprise almost 45% of all Ousteri Lake is located towards north at a distance of fishes. An estimated 15,000 fish depends on freshwater 10 km from Puducherry town (Fig. 1). habitats. Fish forms highest among all vertebral groups apart from its economic importance. India is one of the mega biodiversity hotspots contributing about 11.72 global fish diversity mainly from the greater Himalayan range on the north eastern plains, long stretches eastern and Western Ghats. The Indian subcontinent, occupying a position at the confluence of three bio geographic realms, viz., the Palaeartic, Afro-Tropical and Indo-Malayan, exhibits a great variety of ecological habitats, harbouring rich fish faunal diversity, comprising about 2500 species of which 930 species are freshwater inhabitants and 1570 are marine. The Indian species represent about 8.9% of the Fig. 1: Map locating the study area of Ousteri fresh known fish species of the world [4]. water Lake, Puducherry by various human activities due to a high level of