What is your star sign? What are the characteristics of your star sign?
I'm aquarius and they say that aquarians are inquisitive.
Excellent. Aquarians are people born under the the sign of aquarius. Aquarians is a rare word, so you might say ' they say that people born under the sign of aquarius are inquisitive.'
I'm aquarius and thay say that aquarius is inquisitive.
I'm an Aquarius, and they say that Aquarius people (Aquariuses / Aquarians) are inquisitive.