Tips for filleting fish....
Make sure all the scales have been removed and the fish washed
Use a sharp slightly flexible blade knife
Take the head off
Cut along the top edge of the fish using long strokes then using the point of the knife keep close to the bone and use it as a guide, simply follow the bone cutting a bit of flesh free with each cut, work it over the central bone and over the rib bones until it comes free, repeat on the other side.