Availability and Breeding Behaviour of Ganga River Prawn Macrobrachium gangeticum (Bate) and Macrobrachium malcolmsonii (H.M. Edwards)

Abstract

Macrobrachium gangeticum and Macrobrachium malcolmsonii prawn species are only available from May to October in the middle stretches of the Ganga river around Patna. The size ranged from 65-215 mm and 60-225 mm total length respectively. The number of M. malcolmsonii was found comparatively much less than that of M. gangeticum. The maximum number of females recorded is in the size range of 95-105 mm and the minimum is 185-205 mm total length in M. malcolmsonii. Maturity is attained at size 75 mm total length and above in both species. The incubation period in M. gangeticum was recorded in 12-14 days and 14 - 17 days in M. malcolmsonii. The color of the eggs in both the species gradually become lighter when the larvae inside the eggs found are fully developed, the color became slight grey. The M. malcolmsonii hatches during the night but M. gangeticum hatches at late night to day. In this paper, efforts have been made to study the availability and breeding behaviour under natural and controlled conditions of both species. It also attempts to study the spawning, incubation and hatching of said species.