Protein kinase C isozymes are a biologically diverse group of enzymes known to be involved in a wide variety of cellular processes. They fall into three families (conventional, novel and atypical) depending upon their mode of activation. Several classes of zebrafish neurons have been shown to express PKCalpha during development, but the expression of other isoforms remains unknown. In this study we performed immunohistochemistry to determine if zebrafish express various isoforms of PKC. We used antibodies to test for the presence of enzymes that are thought to be preferentially expressed in the nervous system (PKCgamma, betaII, delta, epsilon, theta and zeta). Here, we show that PKCgamma, epsilon, theta and zeta are expressed in the zebrafish CNS. Anti-PKCgamma labels Rohon-Beard sensory neurons and Mauthner cells. PKCepsilon and zeta staining is widespread in the CNS, and PKCtheta and betaII are expressed in skeletal muscle, especially at intersegmental boundaries. Immunoblot experiments confirm the specificity of the antibodies in zebrafish and indicate that the fish isoforms of PKCgamma, betaII, epsilon and zeta are similar to the mammalian isoforms. Interestingly, PKCtheta appears to be similar to PKCthetaII, which, to date, has been found exclusively in mouse testis, but not in the mammalian CNS. Overall, our findings indicate that several different PKC isoforms are expressed in zebrafish, and that Rohon-Beard, Mauthner cells and muscle fibers preferentially express some isoforms over others.