Do I need to make a roux when making crab bisque?

Every time I am in New England visiting friends, anytime I have a bisque, it is never thickened with a roux or white wash, just the natural thickness of good double cream. And I would trust they know how to make their bisques in New England!

The traditional thickener for a bisque is rice, so no you don't need a roux.

I have never made a bisque without a roux! But there are certainly a few ways to thicken a soup, a roux isn't essential.

It's not absolutely imperative, but it does help the overall texture and flavor of the bisque. If you're looking for a way to make bisque GF, I've had success by cooking onions way way down (not browning, but with lots of butter or olive oil) and then blending them with an immersion blender. It's not the nutty flavor of a good roux, but it helps with the thickness and texture.

It's one way of making sure you have a nice, thick soup, but it's not a requirement.