Despite the potential negative effects of inbreeding and the use of inbreeding as a germplasm protection mechanism, little is known about inbreeding depression in penaeid shrimp, including the Pacific white shrimp, Penaeus (Litopenaeus) vannamei, which is the most economically important cultured penaeid species worldwide reported anecdotal evidence of an association between inbreeding and increased deformities, as well as reduced growth and FCR, during the growout of P. vannamei.