Your arms and legs fuse with your body as bright silvery scales cover your skin.
You take the form of a Diminutive fish. See the Polymorph subschool for more details.
As its name suggests, this spell’s most common use is to make a quick getaway in a watery environment, but it also allows a clever druid to overcome a flooded corridor or similar obstacle.
Source: Complete Scoundrel, page 95. A hyperlinked statistics block for the fish was made to replace the lengthy description of changing the statistics block for a toad to a fish.