If you own Underlight Angler, the fishing artifact from Legion, it can be slotted into Fishing Profession equipment in Dragonflight, turning you into a fish every time you enter the water.

Underlight Angler owners will be pleased to hear that you no longer need to have the fishing pole equipped in your main hand. Instead, the rod can be slotted into your Profession Equipment, and you will gain its effects permanently, turning you into a fish whenever you enter the water.

Source: Reddit