Did you study the retinae of the mudskippers ? These fishes in general, but more species ie Periophtalmodon schlosseri and Periophthalmodon septemradiatus are obligate air-breathers.So your molecular and phylogenetic studies may shed light on a more detailed information on the vision process in these fishes

Cheers Giacomo

PS

I enclose my last paper in Zoology describing the presence of the NECs in the gill and skin of P.schlosseri.NECs are putative oxygen receptors in these epithelia