Differences in olfactory system between wild and cultured red sea bream, Pagrus major (Teleostei)

A four-month market survey revealed that at some mariculture centers in Japan, over 90% of red sea bream reared in captivity possess a deformed single nasal opening as compared with normal fish with anterior and posterior nasal openings at each olfactory organ. The deformity occurred at day 32-40 after hatching when the medial and lateral epidermal lips failed to form the septum that separates both olfactory nares. The authors also demonstrated that the fish reared in captivity have no problems feeding on pelleted diet but their wild counterparts do not accept non-living food even under a long period of starvation. Differences in olfactory system between wild and cultured fish are discussed especially in reference to the olfactory system and fish behavior