열대어 제브라다니오 (Danio rerio)의 난발생 및 자치어 형태발달

Morphological of Development Eggs, Larvae and Juveniles Danio rerio

이 연구는 열대 관상어 제브라다니오의 난발생 및 자치어 형태발달을 관찰해 초기생활사를 규명하고자 실시하였다. 난 형태는 원형으로 분리침성란이었다. 난 크기는 1.10~1.28 mm (평균 1.22±0.12, n=30)였다. 수온은 26~28°C (평균 27±1°C)였고, 부화는 수정 후 56시간이 소요되었다. 부화 직후의 자어는 전장이 2.93~3.66 mm (평균 3.45±0.51, n=30)로 난황을 갖고 있었고, 입과 항문이 열려 있지 않았다. 부화 후 3일째는 전장 3.65~4.14 mm (평균 3.99±0.34)로 난황이 흡수되었고, 입과 항문이 열리면서 전기자어기로 이행하였다. 부화 후 5일째는 전장 4.29~4.55 mm (평균 4.39±0.18)로 꼬리 끝 말단부분이 위쪽으로 휘어지면서 중기자어기로 이행하였다. 부화 후 20일째에는 전장 9.12~12.4 mm (평균 10.9±2.31)로 꼬리 끝의 척추말단 부분이 45°로 완전히 휘어지면서 후기자어기로 이행하였다. 부화 후 25일째 치어는 전장 13.2~15.9 mm (평균 14.0±1.90)로 각 부위별 지느러미 줄기 수는 등지느러미 9개, 뒷지느러미 14개, 꼬리지느러미 19 (9+10)개, 배지느러미 7개로 정수에 달하면서 치어기에 달하였다. 제브라다니오 후기자어는 흑색소포가 대부분 소실된 점, 비늘이 발달한 점, 등지느러미와 뒷지느러미가 발달한 점에서 비교한 잉어목 어류 후기자어들과 형태적 특징에서 차이를 보였다.

This study was conducted to investigate the early life history by observing the egg occurrence and development of autonomous fish form in the tropical ornamental fish Danio rerio. The egg form was circular and was a separately invasive egg. The egg size was 1.10~1.28 mm (average 1.22±0.12, n=30). The water temperature was 26~28°C (average 27±1°C), and hatching took 56 hours after fertilization. The ruler immediately after hatching had egg yolk with a total length of 2.93~3.66 mm (average 3.45±0.51, n=30), and the mouth and anus were not open. On the 3rd day after hatching, the egg yolk was absorbed with a total length of 3.65~4.14 mm (average 3.99±0.34), and it was transferred to the preflexion larvae as the mouth and anus were opened. On the 5th day after hatching, the total length was 4.29~4.55 mm (average 4.39±0.18), and the tail end was bent upward and it transitioned to the flexion larvae. On the 20days after hatching, the total length was 9.12~12.4 mm (average 10.9±2.31), and the vertebral end of the tail was completely bent at 45° and it was transitioned to the postflexion larvae. On the 25 days after hatching, 13.2~15.9 mm (average 14.0±1.90) in total length, and the number of fin basins in each part reached the number of dorsal fin 9 rays, anal fin 14 rays, caudal fin 19 (9+10) rays, and ventral fin 7 rays, reaching the number of fish in each region and reaching the number of fish in the form. D. rerio postflexion larvae differed in morphological characteristics from those of Cypriniformes compared to the postflexion larvae in that most of the melanophore were lost, the development of scales, and the development of dorsal fin and anal fins.