is it safe? are they okay together?

Nah.. i don't recomend it. Arn't they tropical anyway?, you should just keep your goldfish alone maby with a snail or some type of compatible algea cleaner.

Swordtails would probably nip your goldfish's body or fins. I tried it a long time ago and it didn't work. They are too nippy.

Yep, swordtails are a bit nippy. I don't recomend it. They'd just hurt your goldfish.

hehe. yeah from first post, i already did a thumbs down on it.