ABSTRACT
Approximately 80 distinct unisexual biotypes of fi shes, amphibians and reptiles are presently recognized (Alves et al., 2001). However, only eight unisexual fi sh species are known (Table 52). Unlike amphibians and reptiles, all the unisexual fi shes are readily amenable for rearing and experimentation. In fact Hubbs and Hubbs (1932), the fi rst discoverers of unisexual vertebrate, have reared and experimented with the Amazon molly Poecilia formosa for 15 years. Not surprisingly, a relatively large volume of literature is available on the unisexual fi shes (Pandian, 2010).
