This is my 3rd octopus.I don't know how old she was when I got her but she was about the size of a quarter overall.She lived in a 12 gal. nano tank until she grew up some.She seems to be happy in the 30 gal. for now.If she grows any more then I'll get a bigger tank,my husband will have my hide if that happens.We already have a 150,135,2-30,and 12 gal.Any time we're in the kitchen she has to sit in the front of the tank and watch what everyone is doing.Feeding time she comes to the top and flips upside down waiting to be fed.She has to hold your hand while she's eating or if you are doing anything in the tank.She is so cool.You will definately enjoy yours if you take the time to get to know it.