Pseudobranch
The pseudobranch is anatomically related to,
and resembles the gills, but is not involved with
respiration. The pseudobranch is located on the
dorsal section of the inner operculum, and may
or may not be superficial enough to be seen
grossly. In cyprinids, it is deeply embedded. The
pseudobranch is a hemibranch, only containing
filaments on one side. Proposed functions inelude
provision of gases/oxygen to the eye, osmoregulation,
or sensory capability, but these
are still debated. Some clinicians believe pathophysiology
of the pseudobranch may contribute
to idiopathic exophthalmia in some species.