My kids all grew up fishing. I learned from my Dad how to start them out and what to do to get them hooked, so to speak. You see, he had done the same thing for me, and his uncle before him for even him. The kids all love to fish today, although, not unlike most of us, work and family situations prevent fishing as much as they would like.
So what was it that my Dad did and that I did that made a difference? Let me give you a few tips.
First of all, start them young. Get them in a boat, or on a pier, or on the bank at as young an age as you possibly can. Obviously this means being extremely conscious about their safety. Whatever you do, DON'T plan on any fishing yourself. If fishing is going to happen, the fishing will be done by the kids with your help! This lets you pay attention to them and not ignore them while you fish. I see too many parents getting frustrated with children who are "getting in the way" of their fishing. "Just get to the front of the boat and stay out of the way," one father said. And the son did exactly that. My guess is he never turned into much of a fisherman with encouragement like that.
Next, make sure you plan the first trips to someplace that you can actually catch a lot of fish. At this point, it doesn't matter what kind or how big, just make sure they can catch some. A small child's patience is very short, and waiting 30 minutes for a bite will turn them off in a hurry. You may need to go to a small pond where the bream are dying to eat bread balls. Any type of fish will do. Remember, this is for them, not for you.
As they fish, brag and cheer for every fish they catch. Make a really big deal out of it. Take pictures. And if its at all possible, take some home to clean. Let the child help you clean with a table knife, so he can't get hurt. My son was helping me clean snapper at about 2 years of age and he was really working out with that table knife trying to cut that fish. His grandmother asked him what he was doing, and he said, "I'm cutting the fish's face off." Grandma had to retreat back into the house to laugh!
Make sure he makes and sees the connection from catching to cleaning to cooking. As soon as you have the fish cleaned, it's into the kitchen to start cooking. I even let him flour and cornmeal the fish. Let him see the fish cooking, and talk about how good they are. Then when its ready, make sure you brag on the fact that HE(or she) caught these fish, and "aren't they good?!"
Once you do this routine several times, he will be dying to go with you, and will be waiting for you when you get back "Daddy is fishing today where you might get hurt - so you can help me clean the fish when I get home", tells them they can't go this time, but gives them something to look forward to. They will be waiting at the window looking for your return - maybe even having told Mommy to "get my cleaning knife ready".
Now back to the hot boat I was talking about. Yes, I was stupid enough to have my son with me that day. I thought he would burn up in that sun with his tender skin. I could have ruined it that very day, but luckily he had already been several times and caught a number of fish. Had that been his first outing, his mind would equate fishing to heat, discomfort, and boredom, and he would likely not want any part of this thing that Daddy does.
As your child grows older, make sure you equip him or her to fish. He needs "his own" rod and reel, tackle box, and fishing hat. Of course as he ages, those items will escalate in price, but its worth the money, believe me.
I could have been in a lot of trouble when I was growing up. A number of my high school friends did some really foolish things, things they regret. But my Dad had me fishing, and its awfully hard to get in trouble when you're fishing with your Dad.