Hi, I have a 12 gal unplanted nano with 4 golden barbs and 3 plattys. Eight weeks ago one of the plattys had fry and I have managed to keep one alive in the tank but in a nursery box. How do I know when she is big enough to put in the general population? This will be the last fish I add so I want to do it right. Thanks for your help! *SUNSMILE*