FEEDING HABITS AND REPRODUCTIVE BEHAVIOR OF ZIG-ZAG EEL MASTACEMBELUS ARMATUS (LACEPÈDE, 1800) FROM THE BURHI GANDAK RIVER IN BIHAR, INDIA

Reproductive and feeding biology of zig-zag eel

Abstract

This research paper reports on a twelve-month study conducted from July 2019 to June 2020 on the biology of M. armatus from the Burhi Gandak river of North Bihar. The study examined the feeding habits, gastro-somatic index (GaSI), reproductive biology, size at maturity, gonado-somatic index (GSI), and fecundity of 380 individual samples of M. armatus, including juveniles, males, and females. The specimens exhibited a wide range of sizes and weights. Juveniles measured 13.86±0.65 to 27.45±0.58 cm in length and 11.08±1.49 to 52.25±3.16 g in weight. Males measured 36.71±0.82 to 48.73±1.67 cm in length and 90.14±4.04 to 157.88±29.66 g in weight. Females measured 40.42±3.35 to 51.98±1.36 cm in length and 96.28±5.74 to 162.04±10.29 g in weight. The results showed that M. armatus is a carnivorous species with a diverse diet consisting of prawns, crab parts, aquatic insects, chironomidae larvae, bivalves, and small fishes. GaSI and GSI were calculated, showing variations in relation to size and sex throughout the study period, influenced by seasonal and physiological factors. The overall male-to-female ratio was 1.25:1, slightly deviating from the ideal ratio, with males being slightly more abundant. The study identified periods of maturing, spent, and mature individuals, with peak spawning occurring in October 2019, April 2020, and June 2020. The monthly mean absolutefecundity of 78 mature females ranged from 513.40±513.40 to 5895.63±626.11 eggs. The study also revealed variations in feeding intensity, gonadal development, sex ratio, and fecundity among different months. Overall, this research provides valuable insights into the feeding and reproductive behaviour of M. armatus, contributing to a better understanding of this species ecological and biological characteristics.