CEPF Western Ghats Special Series: Reproductive biology of Puntius denisonii, an endemic and threatened aquarium fish of the Western Ghats and its implications for conservation

Abstract

This study presents fundamental information on the reproductive biology of Puntius denisonii, an endemic and threatened aquarium fish of the Western Ghats Hotspot. Results are based on the observations from three river systems, Chandragiri, Valapattannam and Chaliyar. Maximum observed total length in P. denisonii was 162mm and 132mm for males and females, respectively. Males attained sexual maturity at a lower size than females with mean size at first maturity determined as 85.33 plus or minus 1.52 mm for males and 95.66 plus or minus 1.15 mm for females. Puntius denisonii spawned from October to March with minor differences in the peak breeding months between the three river systems, which were studied. Sex ratio deviated significantly from 1:1 and was skewed in favour of males. Absolute fecundity varied from 376 (fish of 102mm total length) to 1098 (fish of 106mm total length) eggs. Currently, the closed seasons for P. denisonii have been put in place during June, July and October based on the (mis)assumption that the species breeds during these three months. However, the results of the present study have helped us to understand more about the reproductive biology of the species so as to recommend more appropriate seasonal closures. The months from October until March need to be designated as a closed season for protecting the breeding population of P. denisonii.