On the breeding behaviour and reproduction of the freshwater prawn,Macrobrachium rosenbergii (de Man 1879) (Decapoda‐Crustacea) under laboratory conditions

The giant freshwater prawn, Macrobrachium rosenbergii is one of the most common decapod species, and now getting more attention from the aquaculturists world wide due to its high market demand. It is commercially important because of its size as well as its eating flesh qualities. The breeding behaviour, reproduction and hatching of this species were observed for about 8 months during 2009. Juveniles (0.55 ± 0.177 g total weight and 2.7 ± 0.12 cm, total length) were reared in rounded fibre glass tanks (1.3 m, diameter). Pre‐mating moult occurs in prawns once the ovaries ripen in their carapace cavity so as to transform the prawn into berried stage. Recorded incubation period ranged from 18 to 24 days. The number of eggs ranged from 2050 to 150 500 and the fecundity ranged from 435.2 to 3849.1 eggs. Number of hatched larvae ranged from 1825 to 123 410 larvae for females of 4.71 to 39.1 g respectively. The number of eggs carried by female prawn was directly proportional to its body weight (no. of eggs = 3441.3 wt. of female – 32 292, r² = 0.819). (fecundity = 82.066 wt. of female ? 235.04, r² = 0.7779; fecundity = 317.86 length of female ? 2651, r² = 0.833). Hatching rate ranged from 65% to 91%, and there was a correlation between number of hatched larvae and size of female parent (no. of larvae = 10 369 length of female – 102 965, r² = 0.8159; no. of larvae = 2792.9 wt. of female – 26 268, r² = 0.829). This study can greatly help in the management strategies of prawn hatcheries and improve its hatching technology.