Colombo, G. and Grandi, G. (1996) Histological study of the development and sex differentiation of the gonad in the European eel. Journal of fish biology, pp. 493-512
| Species | Development state | Trait | Primary Data | Secondary Data |
| Anguilla anguilla | Male | Length at sexual maturity | On average less than 45-50 cm | 47.5 cm |