The Pisces symbol (also called Pisces glyph) is a shorthand representation of the Pisces fish (see below). However, as with the animal itself, much is based both in interpretation and the preference of the writer, and can range from simple to extravagant.
The astrological symbol for Pisces represents the two fish. Above are some examples of commonly used styles for the Pisces symbol. Each of these is equally valid - there is no 'correct' version as long as the general shape is maintained.
Origins of the zodiac symbols and signs
The word 'Zodiac' means circle of animals (though note a couple of signs aren't animals in the normal sense). These 'animals' were based originally on the pattern of the stars in their corresponding star constellation. Basically what the earliest astronomers and astrologers saw when they squinted at the night sky.
Due to this although Pisces will always be represented by two fish (traditionally swimming in opposite directions), there isn't any one 'correct' shape or design for those fish. It's a cosmic game of join the dots, and some constellations even have alternative ways to form the zodiac animal from the dots (stars).
Pisces the fish
Any picture of the shape, heads, concept or profile of one or two fish can therefore be comfortably used here. Designs range from the space-age to the ancient, and are limited only by the imagination of the artist, as long as it gets the point across. In the case of Pisces typically there is also the concept of movement in opposite directions, often with a line connecting both fish.
Below is a representation of Pisces the fish (and the Pisces symbol, inset) from a medieval wood carving from the 16th century. While it's not suggested this is a great picture (hey, you try carving something into the side of a tree which will look sexy in 400 years time!) it does show how the basic concept of Pisces, fish and opposition hasn't changed much over the centuries.
We have a separate article on Pisces tattoos