The ontogeny of the characiform fish Moenkhausia sanctaefilomenae, from early embryogenesis through the early larval period, is presented. Fertilized eggs were slightly elliptical, measured 0.6 mm in diameter, and were surrounded by a fertilization envelope 0.8 mm in diameter. Much of the early embryogenesis is complete after 12 h, with cleavages complete after 2.5 h and gastrulation complete after 3 additional hours. The initial formation of organs needed for predatory behaviors occurs within 72 h. Growth of the cranial elements is quite dramatic and allows for the capture of relatively large prey at the onset of exogenous feeding. Elaboration of these elements continues into the early larval period.