The pattern of incorporation of labeled valine into goldfish brain proteins was compared for animals trained in a new swimming skill with controls. Double labeling studies followed by electrophoretic separation of the proteins on SDS-polyacrylamide gels, showed that there was a consistent increase of valine incorporation for the trained animals at 3 band positions on the gels. These alpha, beta, andnu bands correspond to molecular weights of 37,000, 32,000 and 26,000 daltons. The protein changes were confined to the brain cytoplasmic fraction, in that they were absent from the brain nuclear, brain synaptosomal, and kidney cytoplasmic proteins. Such protein changes were not obtained for a variety of control behavioral situations. The results suggest that there is higher rate of synthesis of specific proteins in goldfish brain following the acquisition of a new pattern of behavior.