Crustins are diverse group of antimicrobial peptides (AMPs) that have numerous isoforms mainly identified from hemocytes in decapods crustacean. However, little is known about its presence solely in gills tissue. In this study, we found two new crustin isoforms MjCRS8 and MjCRS9 by using transcriptome analysis from gills. Open reading frame of MjCRS8 and MjCRS9 were 593 bp and 459 bp encoding 197aa and 152aa, respectively. Tissue distribution analysis indicated that both MjCRS8 and MjCRS9 are expressed only in gills tissue. Multiple sequence alignment and phylogenetic analysis with previously reported crustin suggested that both MjCRS8 and MjCRS9 belong to type 2 crustin family. Experimental infection was conducted against Vibrio parahaemolyticus and white spot syndrome virus (WSSV) by immersion test. However, no significant upregulation was observed.