Thanks for all the advice

Thanks Mats. They've been in for 2 weeks now, so perhaps I am expecting too much too quickly!

I collected a breeding group of 19 Corydoras Sterbai from a seller two weeks ago.
I have tried to induce some egg laying by doing water changes twice a week (25% at a time) but to no avail. I've used quite cold water from the tap (obviously dechlorinated first).

Does anyone have any hints on what ...