Moulting in the grow‐out of farmed shrimp: a review

Abstract The importance of moulting for growth in farmed shrimp is reviewed in relation to the physiological cycle, induction triggers, behavioural and compositional changes, elements for successful moulting and potential strategies for moulting management. Successful ecdysis is also dependent on pond water quality, health and nutritional status. The stages in the moulting cycle are as follows: premoult, the preparation period for moulting that comprises the longest period in the cycle and includes accumulation of nutrient reserves; post‐moult, short and crucial stage for shrimp recovery after moulting; and intermoult, when feeding is continuous and most of growth occurs. The ecdysis is very rapid and mainly dependent on suitable physiological status of individuals. Up to 10% of the whole shrimp moulting cycle may rely on body nutrient reserves, once feeding is decreased or ceased (premoult and post‐moult). Moulting is started by hormonal increments in haemolymph, 20‐hydroxyecdysone and methyl farnesoate, which are found similar in insects. Beyond health and nutrition, proper environmental conditions such as good water quality are essential for successful moulting, hardening of exoskeleton and rapid growth. Moulting prediction and management may result in significant feed savings in pond farming and potential effects of, for example, moon phases and stressors have to be further considered. The complex nature of moulting in shrimp, including different sorts of endocrine regulation and environmental stimuli, suggests it is difficult to be precisely controlled in farmed populations. Moulting physiology of shrimp is discussed in relation to some farming practices.