Gonad structure and reproductive cycle in the deep-sea hermaphrodite tripodfish, Bathypterois mediterraneus (Chlorophthalmidae, Teleostei)

Examination of 122 specimens of the deep-sea fish, Bathypterois mediterrane us (Teleostei, Chlorophthalmidae), collected in the eastern Mediterranean a nd ranging from 35-158 mm SL, revealed that organization of the hermaphrodi tic gonad is first noticable in fish of 60-65 mm SL. At this stage, the two parts of the twin gonad are formed by elongated testicular and ovarial pri mordia enveloped in a common mesodermal tunic, Maturation of testes and dev elopment of eggs are described. The ovary is monocyclic, producing one spaw n of approximatly 2400 eggs from the end of September to the beginning of N ovember.