The

Crystal violet does not inhibit in vitro multiplication of a nonpathogenic strain of Cryptobia salmositica at low concentrations (0.01 μM and 0.001 μM) but multiplication is inhibited at higher concentrations (≥ 0.05 μM). In contrast, the pathogenic strain of C. salmositica does not multiply in vitro when incubated with crystal violet (0.001 μM, 0.01 μM and 0.05 μM). The infectivity of the pathogenic strain is significantly reduced after in vitro exposure to crystal violet. Crystal violet lyses C. salmositica (100.0 μM ) and causes lesions on mitochondrial and nuclear membranes of the parasite. Pathogenic strains of Cryptobia salmositica and C. bullocki are more susceptible to lysis after in vitro exposure to crystal violet than are nonpathogenic strains of Cryptobia salmositica and C. catostom