Preliminary Estimates on Length-Weight Relationships and Condition Factor of Commercially Important Fishes from a Tropical Reservoir, Kerala, South India

The study presents the preliminary estimates on length-weight relationship (LWR) and condition factor of five commercially important species Labeo catla, Labeo rohita, Cirrhinus mrigala, Oreochromis niloticus and Etroplus suratensis from a tropical reservoir, Meenkara, Kerala, South India. A total of 487 individuals of fishes were collected from August 2019 to March 2020 using gillnets with mesh sizes ranging from 120, 150, 200, 250 and 300 mm. The growth coefficient (b) values ranged from 2.52 for C. mrigala to 3.04 for L. catla. All linear regressions of LWR were statistically significant (p < 0.001) with a coefficient of determination r(2) >= 0.900. The results revealed isometric growth for L. catla and L. rohita; negative allometric growth for C. mrigala, O. niloticus and E. suratensis. The condition factor (K) and relative condition factor (Kn) were estimated to be greater than 1, indicating the wellbeing of the studied fishes in Meenkara Reservoir. The study provides the first estimate of the LWR of E. suratensis from an Indian reservoir, as well as the LWR of Indian Major Carps (L. catla, L. rohita, C. mrigala) from a reservoir in Kerala, South India as per the records in FishBase and other published studies. The information from the present study will be useful to assess the growth and population parameters for the management and conservation of these species in Meenakara reservoir, as well as for comparing the LWR data from other inland waterbodies.