Vertebral Anomalies in the Cyprinid Fish, <I>Tribolodon hakonensis</I>

Komada Noritomo

doi:10.11369/jji1950.29.185

Vertebral number and the incidence of vertebral anomalies in newly hatched Tribolodon hakonensis collected from the Nagara River and incubated at various water temperatures (15°-25°C) were examined.The vertebral number of the fish incubated at 22°Cwas lower than that at high (25°C) and low temperatures (15°C, 18°C).The frequencies of vertebral anomalies in 11 N 18mm SL fish incubated at 18°Cand at 25°Cwere significantly higher than those at 22°C.The frequencies in natural populations were basically similar to those at 17°-22°C.<BR>The commonest type of vertebral anomalies in hatchery-reared fish was a helical suture of the centra.The incidence of helical sutures of vertebrae located in the middle part of vertebral column was higher than in the other regions, in 11-18mm SL fish reared for two months after hatching.The frequencies of fused vertebrae and the incidence of fused vertebrae throughout the vertebral column in 18-30mm SL fish reared for 3 and 4 months after hatching were similar to those with helical sutures in 11-18mm SL hatchery-reared fish.The centra showing helical sutures in 11-18mm SL fish were fused together during the next period, 18-30mm SL.There-fore, helical sutures are one cause for fused vertebrae in T.hakonensis.

Vertebral Anomalies in the Cyprinid Fish, <I>Tribolodon hakonensis</I>

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