Paradise fish, macropodus opercularis, were given inescapable shocks in the black side of a two-compartment box. Following training they showed acquisition of a target-striking instrumental response which permitted them to escape from the black compartment to a white compartment. Non-shocked control Ss also showed evidence of learning, probably based on an exploratory drive, but their behavior was far less persistent than that of the experimental group. The results are compared with those of other studies, on both the fish and mammals, which have investigated the effects of conditioned fear training, and some theoretical implications are drawn.