Reproductive performance of Macrobrachium rosenbergii females in captivity

The breeding frequency. fecundity, egg hatchability. larval output and viability of pond-reared, mature Macrobrachium rosenbergii females were individually followed up during 180 d. Sexually mature prawns were maintained under controlled laboratory conditions (28.7 C and 12-h light/d) in a 190-L freshwater recirculation system and fed a formulated diet. Ovarian development. moulting and spawning events were checked daily. Ar least six consecutive moults were recorded for each of the 18 females. The duration of the intermoult period averaged 27.5 d and was not affected by ovarian development or spawning. but intermoult periods followed by spawning had significantly lower growth rates. From a total of 126 moulting events recorded, egg laying successfully followed 76 (60.3%) of them. The number of eggs per spawn (NES) varied from 26.587 to 74.775 for females weighing 20.0 to 55.8 g. The relationship between NES and female size (W: in g) was found to be NES = 484 + 1454W (r(2) = 0.74). Results suggest that the number of viable larvae produced per egg clutch may he increased by in vitro incubation, as the losses of eggs. which usually occur under in vivo incubation, are prevented. The present study illustrates that under adequate and stable rearing conditions, M. rosenbergii females are able to spawn up to five times during 180 d. in comparison to three to five times per year as reported for wild prawn populations.