Egg-laying and hatching rhythms in the monogenean Diplozoon homoion gracile from the southern barbel (Barbus meridionalis).

Diplozoon homoion gracile from the southern barbel (Barbus meridionalis) displays an egg-laying and an egg hatching rhythm, the latter being more clearly defined. Egg laying continues both day and night but significantly more eggs are laid at night. The oncomiracidia hatch at dusk. If parasite eggs are eaten by the host they pass through the gut undamaged and hatch normally.