I've had my giraffe cat for about 10 months. He's gone from 16" to at LEAST 20", but probably more. His mass has probably doubled at minimum. I just moved him to my 600 gallon tank about a month and a half ago. He is one of my favorite fish, and has some serious 'tude for a catfish. He pushes around all of my other catfish and they are TSN, RTCxTSN and ripsaws ranging from beefy 20-27"+. He's a super friendly, eating and pooping machine (poops are up to the size of a land cat's). He is one of the most active swimmer I own and digs in the sand leaving behind little craters. He will eventually outgrow my 600 and be moved into at least a 3,000 gallon pond as they can get to 3' with massively thick bodies. If you can house them, they are GREAT fish, but they really need big homes.