Definitely side-light, if you want to highlight the scales.
High grain and contrast? Maybe you should push a 400 speed B&W a couple stops. There's always Rodinal if you
really want to invite the grain.
You could bracket a few exposures in order to get the right effect you're looking for with high contrast. Too much or too little light changes the image a lot when you're at a very limited exposure latitude.
If you have a specific texture in mind you might also consider a double exposure or overlaid frame of an evenly-lit material of that texture.
For really extreme contrast, you can use a copyfilm like Agfa Copex Rapid, but it won't give you much grain. You could add grain with the overlaid texture.
Just throwing some ideas.