knowledge of the molecular regulatory mechanisms is limited. This is due to the relative lack of species-specific molecular tools and functional studies. Also, an extra level of complexity is observed due to whole genome duplication (WGD) and a rediploidization event which teleost fish have undergone during evolution (Volff, 2005). This has resulted in both ortholog and paralogue genes being retained in extant species (Amores et al., 1998; Jaillon et al., 2004).