Hello Dorothee,
the female leaves the tank the next days. The male leaves the tank at the day the larves swim free – if not go wrong.
This system runs with quindecim very well. (ca.130 young at this time)
Some problems i see with the many Hydra.
Last week i saw one of boraras-brigittae larve in an other tank – inside a hydra 🙁
Quindecim larves are to big for the hydra, i think – but phoenicurus larves ?