The purpose of this research was to determine how a simple antigen can shape the antibody repertoire in rainbow trout. Specifically, we sought to identify shared and unique responses to TNP (VDJ family and CDR3 amino acid utilization) in four high-responding fish. B cells from the vaccinated fish were cell sorted by flow cytometry to separate the TNP-specific and TNP-nonspecific populations from the pre-sorted population. This further allowed us to study clonal expansion and affinity maturation in the animals.