Tridents seem to be able to be enchanted with all enchantments.

It seems as though using a anvil you can enchant Tridents with any enchantment book. This is presumably not supposed to be the case as most of these books (Protection IV, Thorns, Piercing, etc.) don't work with the Trident.
For the image taken I was on a normal super-flat world in creative mode. I have not tested this in survival/adventure mode.