Keep the adults in one tank and fry in the other I find it's easiest to put the ready to drop females in the fry tank that has one half completely packed with fake plants and caves pack it from top to bottom (they sleep near bottom alot of times andhide and play on top in the day, I use mine for feeder fish for pirihanna and even tetras enjoy a few every once in a while, I have countless guppies and generations of fry doing it this way in a matter of months and it's almost too many lol, chainstores usually won't buy em if ur in Canada pets unlimited only gets there stock from quebec but small stores will buy em usually just a trade of store credit though have bought entire new aquariums with this process can only make like 50 bucks a run though but it adds up quick if ur an addict and sell to multiple stores, show guppies make big money sometimes can get up too 50 dollars a piece for nice male proven breeders but the work needs to be dedicated and have a way to dispose or cull off or separate from the normal ones, can take up to 10 tanks but it's a hobby to pay for all ur other gear after about a year and multiple buyers, you defiantly won't get rich but it's a reason to go to every store that you can get too and at least pay ur gas (the uk has mad show guppies and parakeets(budgies) and have seen a guppy for up to 150 bucks it's was a sweet one though)