You hold him til he stops wiggling but do you then keep holding him and humiliate him thoroughly? Do you hold his head down on the ground as well as pinning his body? If you just hold him on the ground with his head free it’s not going to work either. And if you’re going to pin him you have to mean it and follow through every single time, no matter what. For a period of time that feels ridiculous to you. He’s not a dog, and while they do learn voice cues, he has to be taught in ways he’ll understand.
I have a very spoiled drake that was a surprise drake. I raised him from hatch, as a lone duckling. (Terrible idea, don’t ever do it.) he was so cute and friendly! Until his hormones kicked in and he wasn’t. He would bite, he would pinch, he would try to mate with my feet... my hand... whatever he could get a hold of. I started pinning him every time he’d run up to me like this; I would also “peck” him with my finger like another drake would if he was trying to assert himself. If he sneak attacked me, I would turn and peck him in the shoulder until he removed himself from my space. It took probably 6 weeks or more, but he is now a respectful but still friendly drake, who will come sit at my feet. If he decides to try to assert himself again, I literally point my finger at him and he moves himself out of my space.
Also. Your duck is biting you. Do not feed him by hand. If feeding treats, place them on the ground or in a dish. Don’t give him any conflicting signals on when it’s ok to grab at your hands, even if it’s to get food.
