People used mollies and guppies to cycle tanks back on the day. I've seen the mollies survive and make babies. Great algae pickers. I've heard the same about guppies but never witnessed it. Maybe "contamination " from a fish store. Or it could be a female mud minnow. Killi family. Good flounder bait. Hope it makes it. It's cool either way. I've done this 40 years and never just had a fish appear.Yeah it looks a lot like that or a gambusia. Still a mystery as to how it got into the tank if it is a live bearer. :face-with-tears-of-joy: