From a technical standpoint, if you can use the word technical here, a fillet is a thin slice which is different than a steak. However fillet is often used to mean to create any sort of edible strip of meat which can include steaks. Here's one internet description:
Have your fish vendor fillet or cut steaks accordingly, if you are not experienced in this area. They will remove the skin, bones and bloodlines from the fish.
Read more: How to Cook Shark | eHow.com
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