I have an African Lungfish that is about 14". He has grown about an inch a month since I've purchased him.
He has an easy-going temperment. I currently have him housed with a 6" pleco, and they get along fine. However, I used to have hundreds of snails in the tank, including several large snails (4"+), and as of yesterday, he has eaten ALL OF THEM.
I suspect this is a pattern with them.