DAO prepress abstract  -  DOI: https://doi.org/10.3354/dao03208

Survival rates and the occurrence of larval malformations, including Siamese twins, following fertilization of post-ovulatory ageing oocytes in ide Leuciscus idus

Joanna Nowosad, Mateusz Sikora, Dariusz Kucharczyk*

*Email: darekk56@gmail.com

ABSTRACT: Embryonic development of lower vertebrates can be influenced by many factors, especially when outside of the mother's body and under the influence of variable abiotic and biotic factors. In this study, the effects of fertilization of post-ovulatory ageing (over-matured) oocytes of ide Leuciscus idus on the possibility of developing anomalies of ide larvae were assessed under controlled conditions. There was a negative effect of delayed fertilization post-ovulatory ageing (over-matured) oocytes in the ovary on the quality of offspring, which caused reduced survival on 3rd DPF and on hatching stage (68.3 vs. 81.2% and 47.2 vs. 79.7% from over-matured and matured groups, respectively) and increased the occurrence of numerous developmental defects (19.3 vs. 0.8% from over-matured and matured groups, respectively), including the development of Siamese twins. This is the first reported case of the occurrence of Siamese twins in ide. The ide Siamese twins look like hen eggs with two heads and are different from “typical” Siamese twins in fish.