Altums can get to be 15" tall no problem. They are also very limited in the hobby. Many think they have the altums, but they are actually just scalares that have the head hump. THere is also a tall variety of scalare that can reach very tall sizes as well. I had a tall scalare male that when he was the size of a half dollar body wise, his fins stood 8" tall, his mate a silver scalare was only 6" and about 3" in diameter of the physical body.