I shot a crop sensor camera a few years ago in Lembeh. In my experience, to get a pygmy you'll need your 100mm (or 105? whatever it is for Canon) and a pretty strong wet diopter on top of it (assuming you don't want to crop 2/3 of the image).
While you can flip the wet lens out of the way, getting a shark with a 100 or 105 is not the right tool for the job. Too close and you only get a little of the shark, too far and you have way too much water between your lens and the shark.