For 40 years there have been problems in diagnosing sexual patterns in the serranid genus Paralabrax. Difficulties stem from a combination of factors including terminology, histological and morphological characteristics, and the complex inter-relationships in the Serranidae between gonad morphology, phylogenetic position and gonad function. A detailed study of four species of Paralabrax: P. maculatofasciatus, P. nebulifer, P. auroguttatus and P. clathratus, clarifies the problems and improves the diagnosis of sexual pattern in the Serranidae, and for similar families that do not have distinct morphologies for primary- and secondarily-derived males. An hypothesis was developed to account for the multiple appearance of gonochorism in the Serranidae, better known for its widespread hermaphroditism.