Isnt it just? I ended up having 1 danio fry when I had to relocate my danios to treat them against some infection on their gills. I moved them back into the main tank a week later and never really checked my quaranteen tank again untill about a week later my mum told me there was a little fish swimming around in it *shrugs* ... danios breed at weird times
Good luck raising the fry though!