I have a crayfish and some fish from the creek, and a few from the local pet store.
My oldest fish is 1 rosy red minnow from the pet store, one of the 18 cent feeder fish. My 2nd oldest fish is a female western mosquitofish I netted out the creek last summer when it was too small to ID. Meanest fish I've ever had in my life, worse than bettas. So badass she's in a tank by herself with the crayfish.
The queen of my bigger tank is a lone swordtail. She's in there with some wild fathead minnows, some white cloud minnows, and a couple native darter fish I scooped out of a stream this summer.