i got my ally when he was the size of a 50 cent piece. in a yr he was about 4 inches in shell length. at 2 yrs he was approaching 8 inches.....haven't measured him real recently but i will have had him 3 yrs in march and he is around 10 inches or so. the first yr or so he was in my room so the water temp was in the low 80s all the time..i think he grew fast because of the warm water speeding up his metabolism or something. hes in the basement now and the water temp is cooler....low to mid 70s i guess.