It sounds like you may have caught a hickory shad. They are smaller than the American shad and weigh about a pound or two. They will take lures and flies and last year we caught them mixed in with a school of early stripers. They are often caught near the
bottom in the shadows of bridges. If you catch another one look at its bottom jaw. In a hickory shad it will jut out further than the top jaw. Hope this helps.