A gland that is part of a optic choroid. [ OBOL:automatic ]
Teleosts bear a body of capillary adjacent to the optic nerve called the choroidal gland. Though its function is not known, it is believed to be a supplemental oxygen carrier[Wikipedia:Choroid#In_bony_fish].
a gland on the dorsal half of the fish eyeball[http://en.academic.ru/dic.nsf/en_ichthyology/2916/choroid]l