Green-shifting of SWS2A opsin sensitivity and loss of function of RH2-A opsin in flounders, genus .

We identified visual opsin genes for three flounder species, including the spotted halibut (), slime flounder (), and Japanese flounder (). Structure and function of opsins for the three species were characterized together with those of the barfin flounder () that we previously reported. All four flounder species possessed five basic opsin genes, including , , , , and .