The four fish-owls previously in the genus Ketupa were provisionally moved into Bubo as well. However, the mtDNA cytochrome b data suggests that in this case, to make Bubo monophyletic the Scotopelia fishing owls would also need to be included there. On the other hand, the genus then becomes quite large and ill-defined, and Bubo in the expanded sense seems to consist of two distinct clades. Thus, the fish and fishing owls can alternatively be united in Ketupa if some aberrant eagle-owls – at least the barred, spot-bellied and Usambara eagle-owls, perhaps also Fraser's eagle-owl and maybe others – are moved into that genus too. As some enigmatic eagle-owls remain essentially unstudied and others – e. g. Verreaux's eagle-owl – are of unresolved relationships, more research is needed.