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

Abstract

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). Premating 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, r 2 = 0.819). (fecundity = 82.066 wt. of female À 235.04, r 2 = 0.7779; fecundity = 317.86 length of female À 2651, r 2 = 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, r 2 = 0.8159; no. of larvae = 2792.9 wt. of female -26 268, r 2 = 0.829). This study can greatly help in the management strategies of prawn hatcheries and improve its hatching technology.

Response of berried prawn (Macrobrachium rosenbergii) to commercial probiotics

“…Cavalli, Lavens and Sorgeloos () reported that mature M. rosenbergii females at body weights of 20.0–55.8 g can produce 26,587–74,775 eggs. Analogous result has also been observed by Habashy () who noted 2,050–150,500 eggs for females weighing 4.71–39.1 g.…”

“…The eggs of M. rosenbergii , in the present study, hatched out within 21 days but the probiotics treatment promoted this process in less time, that is in 19 days (Table ; Figure ). Comparable studies also reported the egg hatching (incubation) time of M. rosenbergii in 19 days at 26–28°C (Ling, ), 20 days at 28°C (Habashy et al., ), or in the range of 18–24 days at about 28°C (Habashy, ). Other performance indicators of M. rosenbergii breeders include number of hatched larvae, fecundity and hatching rate, and these data were particularly encouraging with probiotics than the control group, that is hatched larvae per spawner was 36,302 ± 323 (probiotics) vs. 33,349 ± 198 (control), relative fecundity (eggs g −1 ) was 545 ± 7 vs. 519 ± 9, and hatching rate (%) was 94 ± 1.0 vs. 91 ± 1.1 (Table ).…”

“…Other performance indicators of M. rosenbergii breeders include number of hatched larvae, fecundity and hatching rate, and these data were particularly encouraging with probiotics than the control group, that is hatched larvae per spawner was 36,302 ± 323 (probiotics) vs. 33,349 ± 198 (control), relative fecundity (eggs g −1 ) was 545 ± 7 vs. 519 ± 9, and hatching rate (%) was 94 ± 1.0 vs. 91 ± 1.1 (Table ). Study by Habashy () determined the number of hatched larvae between 1,825 and 123,410 for females of 4.71–39.1 g. Similarly, fecundity of M. rosenbergii was found to vary from 435.2–3,849.1 eggs (Habashy, ) or to 1,216–89,747 eggs (Jee & Kok, ) for prawns weighing 4.7–45.8 g. But depending on their age, length, weight and environmental conditions, fecundity can be as high as 130,000 eggs (see Jee & Kok, ). The hatching rate of M. rosenbergii was also found to vary from 65% to 91% (Habashy, ) and mature females can produce 80,000 larvae (New, ).…”

“…Throughout the experimental period important physico‐chemical parameters of water were maintained within the guidelines recommended for M. rosenbergii broodstock management (Chowdhury et al., ; Habashy, ; New, ; Nhan, Wille, Hung & Sorgeloos, ). Thus, temperature, salinity, DO, pH, ammonia‐nitrogen (NH 3 ‐N), nitrite‐nitrogen (NO 2 ‐N) and nitrate‐nitrogen (NO 3 ‐N) of the rearing tanks were 28.0–29.1°C, 5–6 ppt, 5.7–6.5 mg/L, 7.2–7.8, 0.02–0.18 mg/L −1 , 0.03–0.12 mg/L and 7.0–13.0 mg/L respectively (Table ), and the data between probiotics and control groups do not differ significantly ( p > .05).…”

On the safety of RNAi usage in aquaculture: The case of all-male prawn stocks generated through manipulation of the insulin-like androgenic gland hormone

“…Furthermore, the neo-females presented no significant fecundity changes relative to normal females in terms of the average number of eggs/g total body weight. In this respect, the results of the present study for both normal and neofemales were within the range reported by Habashy (2013), who showed a range of 435 to 3849 eggs/g and also within the values presented by Jee and Kok (1991), (1132 ± 484 to 745 ± 487 eggs/g body weight) in mature M. rosenbergii normal females. The brood somatic index (BSI) was very similar in both groups, implying a normal ratio between prawn egg mass to body weight of the neo-females.…”