Whole goldfish anti-bovine serum albumin (BSA) serum was fractionated to yield two populations of antibody-containing immunoglobulins of different charge. Whole serum protein homologies of the two antibody preparations were demonstrated by Osserman-type immunoelectrophoretic tests. Diffusion-in-gel tests indicated that the two antibody populations shared at least one antigenic determinant, although one population was antigenically deficient with respect to the other. On the basis of their whole-serum homologies and antigenic disparities, the two antibody populations are thought to represent distinct serum proteins.