The "duckmouth" is shown by most of the species naturally occuring in the east coast drainages of Africa (from
O. spilurus in the north to
O. mossambicus in the south) as well as by
O. mortimeri and
O. andersonii. However, it seems not as pronounced in the latter species, as can be judged from the numerous photos of very large adults in the www. See for example here:
http://www.outdoorpages.co.za/gallery/photos/ProfileGallery.asp?SpeciesID=118&MemberID=1&DisciplineID=3&SpeciesName=THREESPOT%20BREAMThe freshly caught juvenile shows the 'threespot' pattern which gave
O. andersonii its common name, but this is also known to occur in other species of the genus, including
O. mossambicus, where the number of spots is variable. The pattern shown by the larger fish, i.e. midlateral and dorsolateral stripe, on the other hand, is not recorded from
O. andersonii of any known provenance. Likewise, the light lower jaw and throat of the adult male are unknown from this species, but are typical to
O. mossambicus. Given that the occurence is most likely no natural one (though a relict distribution in rivers south of the Cunene cannot be excluded with certainty), it is most likely an introduced strain of
O. mossambicus or hybrids between this and another species.