Pisces

It says “Pisces”, not a mood.

Next to a profile name, read the Pisces sign as “I'm a Pisces.” Any dreamy or emotional flavour comes from the surrounding words and astrology stereotypes, not from the symbol itself.

Why is Pisces two fish tied together?

It traces a constellation pictured as fish.

Fish in this patch of sky are ancient: Near Eastern star lore, including Babylonian, linked these stars with fish long before the Greeks. In one Greek telling, Aphrodite and her son Eros became fish to escape the monster Typhon and tied themselves together so they would not be separated; a Roman version has two fish carry them to safety. The glyph is usually read as two fish (the curved arcs) joined by a cord (the straight bar).

Astrologers count Pisces as a water sign, traditionally ruled by Jupiter and, in modern Western astrology, often by Neptune too. In the tropical Western zodiac, signs are fixed seasonal slices rather than star patterns, so they have drifted from the constellations: because Earth's axis slowly wobbles, the Sun now stands in the constellation Pisces at the March equinox, the moment the sign Aries begins. That drift is behind talk of the “Age of Pisces” giving way to the “Age of Aquarius”.