Length-Weight Relationships and Reproductive Biology of Rita rita (Hamilton, 1822) for Conservation from the Brahmaputra River

The freshwater bagrid catfish, Rita rita (Hamilton, 1822), commonly known as ‘Rita’, constitutes a commercially significant food fish species throughout the Brahmaputra River basin and its associated tributaries. In the present study, data on length-weight relationship and reproductive biology containing sex ratio, condition factor, fecundity, hepatosomatic index and gonado-somatic index (GSI) of Rita rita were assessed. Samples were collected from the landings centre located on the bank of river Brahmaputra at Tezpur, river Jamuna at Jamunamukh and river Kopili at Dharamtul from August,2022 to July, 2023. The slope (b) in length-weight relationship equation was 1.87, 1.25, and 1.12 for female, male and pooled suggesting a negative allometric growth pattern. An overall sex ratio (M/F) of 1: 2.70 observed was statistically non-significant. The gonadosomatic index ranged from 0.22-3.81 in males and 0.65-11.45 in females, both showing peaks in the month of July. The hepatosomatic index (HSI) varied from 0.88-1.35 in male, 1.34-2.14 in females and 1.09-1.59 for the pooled sample, the value of HSI index gradually decreases with increase of GSI in both male and female. The fish was highly fecund and the fecundity ranged from 10445.88 to 26262.52 eggs with an average of 16,865.89 ±73.8. The fecundity was found to increase with the increase of total length, body weight and the ovary weight and the relationship was linear and significant among them However, the relative condition factor >1 suggested the species to be in good condition throughout the year in both the males and females.