Shrimps of the genus Penaeus is the most traded, high valued seafood commodity, and it is the focus of the fastest growing shrimp aquaculture. About90% of the global farmed shrimp production is dominated by two major species of penaeid shrimps: Penaeus vannamei and P. monodon. These two species of shrimp belongs to two different groups, characterized by different reproductive features that utilize this morphology. This grouping is based on the difference in the anatomical details of the thelycum, situated at the posterior thoracic somites X11 to X1V of the female, which is used for the sperm deposition through mating and their storage. The objective of this presentation is to evaluate the potential and challenges of the variability in the structure of the thelycum (closed vs open) in two species of genus Penaeus: Penaeus vannamei and P. indicus. Among the twenty eight species of genus Penaeus, only six species have open thelycum that inhabits in the coastal waters of Atlantic and Pacific oceans, and remaining all species possess closed thelycum. In open thelycum species males mate with females having fully reproductively matured ovary and spermatophores are stored for a short duration of 12-24 h, where moulting is not a prerequisite. In the closed thelycum species males mate with recently molted females having undeveloped ovaries, and spermatophores are stored in the thelycum for a considerable long period until ovaries are matured and spawned, here moulting is a pre-requisite. These differences in the reproductive behaviour of open thelycum species is advantageous in captive reproduction as oocytes get opportunity to fertilize with fresh spermatozoa. Conversely in the closed thelycum species oocytes should get matured after mating, and spermatophores are in the stored condition for a considerable long time in the female genitalia. Thus, the quality of spermatophores would decline over the time, and number of available spermatozoa for fertilization of subsequent spawning, naturally gets reduced. This inherent biological disadvantage, is a challenge in the captive breeding of tiger shrimp, and this is reflected in the poor success rate in the domestication of this closed thelycum shrimp. At the same time, open thelycum nature of the American shrimp and related reproductive advantages possibly helped in the selective breeding and successful stock improvement of vannamei This basic difference in the reproductive biology acts as an inter-specific breeding lock when open thelycum species are escaped from an aquafarm during extreme weather conditions such as flooding. Here the potential of hybridization among closed thelycum species is considerably low. However, in vitro fertilization experiments carried out in our laboratory indicate that sperms of open thelycum species are capable of fertilizing the oocyte of closed thelycum species, and successful fertilization was achieved between these two groups. It indicates a possibility of cross hybridization between the phylogenetically species of shrimp such as open thelycum vannamei and closed thelycum white shrimp such as Indian white shrimp (Penaeus indicus). If proven successful, this would open up a new paradigm in the interspecies shrimp breeding.