My apistos were really active this morning, but I thought nothing of it. Just now I wanted to do a water change and noticed the female is quite fiercely defending a crevice underneath a piece of driftwood. She is also much thinner and her colouring has changed.
I'll let you know if I ever get to see wigglers in the following days!
Here are some pics:
It's underneath this piece of driftwood:
A little closer, but I can't take pics of the actual hole they made in te gravel to get underneath the driftwood, it's too dark

Funny they choose this over the coconut cave I provided them with. I guess fish choose their own breeding places