Ive caught them before also, Casted to close to the edge with a 4" pumpkin power lizard and seen something pounce on it. Was a frog. Once pond I walk around gets CHOKED with matted grass and you could see all the frogs moving around. Took the hook off, tied my line around a hula grub and would cast it out..Theyd grab it fight them in shake it they would fall off and repeat. Greedy lil critters cuz some of the ones Id let go would grab it over and over.