IAG was found to be expressed in the AG of male crustaceans, which belongs to the insulin superfamily of proteins and was considered as the key regulator of male sex differentiation [5, 12]. IAG is responsible for the development and continuation of male primary and secondary sexual characteristics, inhibiting the synthesis of Vg and stimulation of spermatogenesis. We found that a unigene from the AG transcriptome sequencing result has 44.2% and 42.4% identity with IAG of Callinectes sapidus and Scylla paramamosain, respectively. Further analysis found that the length of the gene sequence is 1392 bp and ORF length is 456 bp. The amino acid sequence alignment indicated that the novel gene had common conservative amino acids with Callinectes sapidus, Scylla paramamosain, and so forth (Figure 5), which proved the novel gene is IAG of E. sinensis.