Here’s a simple fish blend to help.
Shameless RVK plug.
Hooks are a way to constrain a vertex or a group of vertices in a mesh to follow another object, kind of like pinching someone’s cheek and pulling it away from the face. The object it follows is usually an empty, and it is automatically set to move like the vertices normally would if unhooked.
In edit mode, select the vertices to hook and press Ctrl-H to add a hook. Now tab back out and grab the empty and drag it around a bit to see what happens.
Hope this helps.
Oh yeah, forgot to mention, you can load the blend file, press Z for shaded, and press Alt-A to see him move a little. Try viewing from different angles.[/edit]