The purpose of this study is to investigate the early life history of the
Rhodeus fish, Rhodeus uyekii and
R. ocellatus, in the Nakdong River to use as the
preliminary data for the systematic study. The embryos used in the study were
fertilized eggs (embryo) and larvae after artificial fertilization. The long
diameter of the eggs of the R. uyekii was 3.39-3.97 mm (average
3.68±0.41 mm, n=30) and the short diameter was 1.36-1.55 mm (average
1.45±0.13 mm, n=30). The long diameter of the eggs of the R.
ocellatus was 2.53-2.71 mm (average 2.62±0.12 mm, n=30) and
the short diameter was 1.47-1.60 mm (average 1.53±0.09 mm, n=30).
Hatching time was 48 hours for the R. uyekii and 50 hours for
the R. ocellatus given that the average water temperature was
21.5°C. The hatched larvae were 4.95-5.00 mm (average 4.98±0.04
mm, n=5) for the R. uyekii and the total length was 3.66-3.69
mm (average 3.67±0.02 mm, n=5) for the R. ocellatus.
R. uyekii was found to be 15.5-15.8 mm at total length
(average 15.6±0.21 mm, n=5) on the 56 days after hatching with the number
of dorsal fins being iii-9, anal fins iii-10, ventral fins iii-5. The R.
ocellatus was found to be 15.8-16.0 mm (average 15.9±0.14
mm, n=5) at total length on the 58 days with the number of dorsal fins being
iii-11, anal fins iii-12 and ventral fins iii-5 where the number of all fin
stalks reached maximum.