The brooding cycles of Hemichromis bimaculatus and Aequidens portalegrensis are very similar in timing except that the latter have a longer pit young stage. Exchanges of eggs or wrigglers between the two species resulted in ready acceptance of foreign young. Experienced as well as inexperienced pairs raised foreign spawn successfully in alternation with their own or were induced to brood mixed schools. Acceptance of eggs, wrigglers or free-swimming young was limited to those individuals, regardless of species, which matched in age and behavior the parents' brooding phase. Therefore, it is concluded that parent H. bimaculatus and A. portalegrensis are not imprinted on the species characteristic of their first or subsequent young. Instead, there appears to be an internal mechanism regulating the duration of the phases of parental care, that limits the responsiveness of the parents to particular stages of young.