In most biparental, substrate-brooding species of cichlid fishes, female and male roles differ. Females are usually more involved in direct care of the young while males spend more time away patrolling the territory. This study tested the flexibility of these sex roles with removal experiments in the convict cichlid, Cichlasoma nigrofasciatum. When males were removed, female fanning activity increased. When females were removed, males spent more time fanning and less time away from the brood. Other behavioural variables (frequency of digging, mouthing, foraging and retrieving) were not affected. Being alone or paired during a first breeding episode did not affect parental behaviour during a subsequent episode in which all fish were paired. Observations were carried out during the day and at night, and nocturnal fanning of fry is reported here for the first time. Female role appears less flexible than male role, as befits the more direct care normally given by females.