I've had a lot more guppy fry than anything, and my Balloon-Bellied molly fry were awfully cute, but Swordtail fry are SO colorful--I'd have to go with swords. I presently have one that is a Marigold/Red Wag mix. He isn't red like a Red wag, but he is a brighter, more vivid orange than the Marigolds with a pitch-black tail. He is about the size of a guppy now, and beginning to grow a sword!!