Mirror imagery and biological selection

Lake Tanganiyka has lefty and righty cichlid fish that show there can be natural selection for a trait over its mirror image counterpart.This raises the question ‘Can there be biological selection of a whole organism over its mirror image counterpart?’ That is, could the fitness of a fish be altered by simply changing it into its own enantaniomorph? My answer is no. I present Flatlander thought experiment to demonstrate that mirror imagecounterparts are duplicates because they only differ in how they happen to be oriented in space. The counterparts have the same intrinsic properties and are in the same environment,so there can be no difference in fitness.