This paper characterizes the molting stages of giant freshwater prawn, Macrobrachium rosenbergii under laboratory conditions. Using the distal fifth pleopod as the main reference region and applying Drach’s classification system, we checked the epidermis and carapace hardness and documented major structural changes, such as the retraction of epidermal tissues from the cuticle and setal development. Our findings showed that in early postmolt, no development of seta matrix was observed. A closer examination of seta lumen during the intermolt stage showed that the epidermis was a densely granular structure and the internal cone was developed. In the premolt stage, a retraction of the epidermis from the cuticle (apolysis) and the formation of new seta were recorded. This study shows that using internal seta development changes is apparently a useful, easy, and practical method of determining molting stage in order to facilitate the study of molt-linked processes and metabolism.
