Feeding and reproductive behaviour of the river catfish Rita rita (Hamilton, 1822) in the river Ganga, India

摘要

In the present study, data on food and feeding habits, sex ratio, condition factor, fecundity, maturity stages and Gonado-somatic index (GSI) of Rita rita were assessed. Samples were collected from the landings centre located on the bank of river Ganga at Allahabad from October 2013 to September 2014. An overall sex ratio (M/F) of 1: 0.99 observed was statistically non-significant. Molluscs (49.52% by volume), detritus (41.49%), insects (0.87%) and other miscellaneous food items formed the food of R. rita. In addition to the occurrence of the various food items, small pieces of polythene were found in 3.3% of the total stomachs examined. Food intake was observed to be reduced during the spawning months. However, the condition factor >1 suggested the species to be in good condition throughout the year in both the males and females.The mean relative gut length recorded was 1.6. Fecundity ranged from 21, 066 to 2, 49, 828 with a mean of 79,893 ova. Gonado-somatic index (GSI) was 0.41 to 6.71% and 0.21 to 1.48% for females and males, respectively. Highest monthly GSI in males and females was recorded in the month of July. Higher individual values of GSI along with presence of mature and maturing fishes encountered in the months, May to September showed that R. rita has multiple and prolonged breeding period from May to September with a peak between July and September.