Honestly I am not sure how old I assume a least full grown, I have 2 Grays in this tank now. I have been waiting for a return e-mail from a Herp vet about fecal but no response yet. The first one I think is a female and the second a male. After being placed in the tank a few days later we would here a frog call about 10:30am-11am.....Which only the males call so there has to be one in there. Both are about 1 1/4"-1 1/2" long from what I have read the large ones get about 2". Both eat with extreme velocity. Very cute animals and have started to show themselves a little bit more during the day not much but you can see them. Before you could only see them at night after the light was turned off and sun went down....I have had the first one about 3 weeks and the second 2 both were found in the exact same spot on week later.