Cerebral lateralization has been suggested to convey a selective advantage to individuals by enhancing their cognitive abilities. Few, however, have explicitly compared the cognitive ability of animals with strongly contrasting laterality. Here, we examined the influence of laterality on learning performance in the crimson spotted rainbowfish, Melanotaenia duboulayi, using a classical conditioning paradigm. We also compared the learning ability of wild caught and captive-reared fish to examine the influence of rearing environment on cognitive performance. Laterality was established by observing which eye fish preferred to use while viewing their mirror image. Subjects were then conditioned to associate the appearance of a red light with a food reward over 7 days. Our results revealed that left-lateralized fish learned the conditioning task faster than right-lateralized. These results provide further evidence that cerebral lateralization can play important roles in cognitive function which likely have diverse fitness consequences for animals in their natural environments.