My Male is about 12cm and the female about 8cm and they bred for the first time last month they've both been happily ignoring each other in a community tank with clowns and stuff for months. I just gave him a strawberry pot cave with one tiny opening (a bit larger than his head) which he moved into pretty quick and sat in there cleaning it up a bit then he invited his lady friend in and wahey) I managed to catch a load of the fry just after they hatched and as they were thinking about leaving the cave, didn't try before as I didn't want to spook the male (imo he's vital in getting them to hatch)
I just think your's sound a bit small to worry just yet.