Crustacean culture has been developing rapidly in various parts of the world. Therefore, it is important to understand their reproductive biology. Insulin-like androgenic gland hormone (IAG) secreted from the androgenic gland (AG) is widely accepted as a key regulator of sexual differentiation in male crustaceans. However, recently several sex-related genes (i.e.,CFSH,DEAD-boxfamily,Tra-2,Sxl,Dsx,Fem-1,Soxgene family,Foxl2, andDmrtgene family) have been identified via transcriptomic analysis in crustaceans, indicating that sexual differentiation in crustaceans is more complicated than previously expected. It has been found that several non-coding RNAs (i.e., miRNAs, lncRNAs, and piRNAs) and IAG receptors may be involved in the sexual development of decapods. Identification and study of the regulation mechanism of sex-related genes, non-coding RNAs, and IAG receptors will provide valuable information regarding sexual development in decapods. In this review, the roles of hormonal and genetic factors in both males and females are discussed. In males, crustacean female sex hormone (CFSH),Sxl,Dmrtgene family,Dsx,Soxgene family,GEM,Fem-1, l-GnRH-III, and corazonin play important roles inIAGregulation in the “eyestalk-IAG-testis” endocrine axis. Unlike males, the regulation mechanism and interaction of sexual genes are relatively unknown in females. However,CFSH,IAG,Fem-1,FAMeT,Slo,UCHLs,Erk2,Cdc2,EGFR,Vg,VgR, andVIHseem to play crucial roles during ovarian development. This study summarizes the available information in the field, highlights gaps, and lays the foundations for further studies and a better understanding of the regulatory mechanism of sexual development in decapods.

In recent years, crayfish aquaculture industry has been developing rapidly in different regions of the world. Crayfish aquaculture is often carried out in dams, lakes and extensive pond systems. There is an increasing demand for crayfish juvenile in aquaculture sector. Therefore, it is important to know which factors affect reproductive efficiency in crayfish. In the present review, factors affecting the reproductive efficiency of crayfish are divided into two main sections, external and internal factors. Dietary lipids, phospholipids, highly unsaturated fatty acids, protein and amino acids, vitamins and carotenoids are important external factors affecting broodstock crayfish reproduction. In addition, various external (i.e. female size, stocking density, temperature, photoperiod, sex ratio) and internal (i.e. endogenous hormones) factors affect the reproductive efficiency in crayfish. This study reviews the present knowledge with the purpose of realizing the factors that are important to reach optimal crayfish nutrition, maturation and reproduction (i.e. pleopodal egg number and quality). This review will particularly be useful for crayfish farmers and crayfish hatchery units.