Pitbull mixed with what? One year old.

My other dog is a Pitbull and is the known father. So this dog is half Pitbull. He has webbed toes so there has to be some kind of water dog. His mom barks like a hound dog, but there is a bit of different hounds. His is slightly taller than his dad, the Pitbull, but his mom is shorter than a Pitbull. His mom was found a stray by my boyfriend’s mom and stepdad. The dog’s name is Diesle. Because the black mixed throughout his body gives him a dirty appearance. He is about 45 pounds at one year old, his dad is 52 pounds at three years old, and his mom is 25 pounds at an unknown age, but she is greying in the face. The mom is all yellow, about the same color as a yellow lab. The dad is tan with black mixed through but doesn’t show easily and has some white points.