What do you think of the name Tiber for our new puppy?

He's a Boxer Mastiff mix and is gray with faint tan brindle. (I think his coat looks like a river at sunset) My boyfriend thinks it sounds too much like Tiger, but I think its unique and like the significance. Also found on Wikipedia that the Tiber was named after an ancient king who drowned in it and Zeus appointed him to watch over it for eternity.