It's not fun for a tired kid who's wet and cold to fish. Take plenty of snacks and perhaps some toys. Fishing provides a good time for teaching safety, respect for water, behavior around boats and on a dock, what to do it when faced with a storm, and how to avoid problems and survive. Don't force a child to handle fish or make him or her take them off the hook unless he or she is willing. Then, show him or her how to avoid spines and sharp fins, the teeth of a bluefish, and the possibility of snagging on a hook.
Children learn by imitation.
Show them the safe and right ways. My nephew was so overjoyed at his first fish, a croaker, that he wanted to take it to bed with him, so my wife handed him a towel, told him the fish might be cold and that it needed a blanket to keep it warm. Don't make an issue of little things like sleeping with dead fish. It's a great chance to teach a child how to carefully and respectfully handle a fish if he or she is going to release it. Make sure to heap plenty of praise on the child for learning a new skill and to take a photo of the first caught fish so the child can show off his or her new talents.