Sagittarius

Honestly, it doesn't matter. If you love someone, just go for it! Don't worry about starsigns. Do you think that if you were a Cancer and your mother were a Capricorn and a magazine told her that you weren't a good match she'd disown you? Of course not! She loves you! Don't worry about what the stars say. Follow your heart. However, if you still wish to know:

"Both Sagittarius and Pisces are ruled by Jupiter. This means you have some immediate understanding of each other, and similar ways of thinking. But Pisces is also strongly influenced by Neptune, which makes them dreamy, sensitive and even mystical. This appeals to your Sagittarian idealism: you both feel there's a deeper meaning to life. You could spend a lot of time tuning in to these common interests and building your relationship on them.There are also some significant differences between you. For example, you're far more fiery and outgoing, and you could sometimes push receptive and easygoing Pisces to the point of retaliation. Also, Pisces needs time to take in their surroundings, and likes to dream their dreams at their own pace. This is the opposite of your gung-ho approach - you like to get things done now. You'd rather implement dreams than dream them. This difference could be a sticking point in your relationship.Pisces does relate to the domestic side of Sagittarius, though. This is because Pisces wants to settle into a familiar environment, create a family and get down to the job of living a life that is nurturing. That's not to say they won't enjoy exploring the world with you. The right sort of Pisces will soothe your tempestuous and volatile restlessness and share in the thrill of what you have to offer. The sexual and emotional aspirations of Sagittarius and Pisces have a lot in common, so there can be some exciting moments for the two of you, both inside and outside the bedroom. Sensually speaking, this is a good match. You could have very similar interests to Pisces born between 19 February and 28/29 February. These Pisceans have an intuitive streak, so listen to their suggestions when they get a hunch. This can help develop your relationship, believe it or not. Be on guard when dealing with Pisces born between 1 March and 10 March - their overemotional sensitivity can create disturbances for you. They are finicky about the way you should save or spend your money. Being as free and easy as you are, this won't be easy to adjust to. You'll love mixing with Pisces born between the 11 March and 20 March. They are strongly influenced by Mars, Pluto and Jupiter. There will be something secretive or clandestine about your contact with these Pisceans, though, so be prepared for a rather different type of relationship if you're serious about getting involved with them." - Astrology.com.au

They go together quite a bit yes. E.g. both like to travel and read.

One must also remember that Aquarius is air element, and Sagittarius is fire element. Air can whip up a flame, or put it out.

There are two galaxies refereed to as the Sagittarius dwarf galaxy.

• Sagittarius dwarf Elliptically galaxy: is an elliptical loop shaped satellite galaxy of the Milky Way Galaxy.
• Sagittarius dwarf Irregular Galaxy: Lies about 3.4 million light-years away and is not within the Milky Way Galaxy.