Not knowing what sizes they are but judging from the adult (possibly male) blue gourami, I am guessing the larger one is about 4-4.5” and the smaller 3-3.5 to 4”. If so, they are done growing (but could grow a very little more) and instead can just become thicker. But they certainly can live several decades. Three of my specimens (M. Maculatus) are now about 25 years old.