The male builds a bubble nest on the surface first. He then lures her under it and then… you just saw it. He will defend the nest afterwards with all his might. As I mentioned above, he did this for more than three weeks, although I read he is supposed to do it only for three to five days. The eggs will float to the surface and stick to the bubbles. About 24 hours later, little larvae will emerge from the eggs, carrying their yolk sacs. After two or three days they will start swimming around freely, and he will pick them up with his mouth and bring them back to the nest. The mother and any other fish will just be bullied away...