WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2026 53 mating and egg laying activity takes place. Egg hatching occurs in coastal waters (Hagerman and Ostrup 1980). The marine larval phase is very extensive and longer than that of any other known Macrobrachium species. Post-larvae start migrating from sea water to fresh water after completing larval development. Juveniles become benthic feeders in lower reaches of fresh water streams. Optimum growth occurs at a stenothermal water range of 18-32oC. Feeding habits of Macrobrachium lar were studied in inland water bodies of Andaman Islands by Sethi et al. (2013). Their findings revealed that the species is omnivorous, feeding on both plant and animal matter, with a strong preference for animal protein, particularly among larger individuals. Common foods include detritus, nuts and insects. M. lar is nocturnal, actively feeding at night, while in the day, it typically hides under bushes, stones, rocks and logs. Feeding intensity is higher in the monsoon season. Adult individuals are predominantly predators but when held in tanks they readily consume pelleted feeds, as well as animal flesh such as molluscs, bivalves, fish, crustaceans, and even coconut flesh during the day. In freshwater streams and water bodies of Andaman and Nicobar Islands males range in size from 86 to 112 mm (32–40 grams), while females range from 66 to 106 mm (14–20 grams). Males are frequently found in December-February and September-November while females are more common in February-October in Andaman freshwater habitats (Sethi et al. 2013). The overall average ratio of male to female has been reported to be around 1:2.8. Breeding occurs twice a year, with June and November seeing the greatest number of berried (ovigerous) females. The estimated mean fecundity of berried females ranges from 4500 to 5500 although as many as 20000 eggs have been reported from large females elsewhere. Field observations and experiments have shown that as adults M. lar do not undertake extensive migrations in streams (Nandlal 2010). Culture of Macrobrachium lar Macrobrachium lar culture has not been adopted by farmers in commercial scale. Traditional culture practices like polyculture with other species, and scientific research trials for breeding and culture have been tried in some Asian countries. Monkey river prawn is commonly cultured in Fiji and referred to as the people’s prawn due to its high demand as a delicacy. The commercial culture of this species is generally carried out up to a size of 180 mm. In small Pacific island countries like Vanuatu, monoculture of M. lar is predominantly done in small earthen freshwater ponds (Gereva 2014). Integrated faming of taro and M. lar is a traditional culture practice in swampy areas of this country. Juveniles are captured from creeks and freshwater bodies by scoop net and stocked in water logged swamps, which are planted for taro farming. During the rainy period the taro fields get inundated with water and the juveniles also enter from adjacent natural waterbodies. The prawns are fed on household waste, grated coconut leftovers and cow dung which are applied to the taro field. The prawns are also fed with artificial feed when the culture period is yearround. Harvesting takes place after six months when the taro is harvested and the water is drained completely for capturing the prawns. Partial harvesting is also conducted when farmers block off sections of the taro swamp and drain the water from each section separately. M. lar grows to a size of 20 grams in 4 months, with a survival of 70% in integrated farming systems with taro (Nandlal 2010). Larval Rearing and Culture The complete larval cycle has been standardized using a novel green water technique (Lal et al. 2014). There are 13 zoeal stages before metamorphosis in this species, and more research has to be done on the survivability aspect of its larval rearing. In our work it took around 77 days from zoea I to first decapodid, and larval survival was very poor. The benthic habit of larvae was quite common in the case of M. lar, unlike M. rosenbergii larvae where the active larvae are found swimming. In the early research stages of M. rosenbergii culture, larval survival rates were found to be 16-17% while nowadays 60-80% hatchery survival is being achieved in experimental and commercial RAS. Biofloc along with green water techniques have been used in studies resulting in complete M. lar larval development. But further research is needed in that aspect to provide live feed along with a clear water system. M. lar developed through 13 zoeal stages, with an intermoult duration of 3 days (zoea I to IV), 8 days (zoea V to VIII) and 12 days (zoea IX to XI). Irregular larval development occurred between 21 and 63 days for zoeae XII and XIII. The time taken for the last individuals to reach the decapodite stage was 34 days. In contrast to M. rosenbergii, where the healthy larvae without aeration stay close to water surface, the M. lar larvae showed more benthic dwelling activity in the presence of aeration. Cannibalism was not observed during the larval rearing study, although it cannot be conclusively ruled out. Nandlal (2010) reported that M. lar larvae exhibit cannibalism. The complete feeding in mass larval rearing was not standardised. A different experiment conducted for larval rearing of M. lar with artemia nauplii as live food did not result in survival to the decapodite stage. The mass larval rearing strategies resulted in survival rates of 40–50% in flow-through hatchery systems, 60–80% in Thai backyard hatcheries, and 60–80% in experimental and commercial recirculation systems, with development durations of 29–35 days (Kutty and Valenti 2010). It can thus be expected that there will be room for improvement (CONTINUED ON PAGE 54) FIGURE 2. M. lar life history.
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