Would rosy red minnows be ok in this?

I have a 30 gallon tub pond which is placed in a small patio underneath my deck where it receives dilute afternoon sunlight. It has a filter rated for 45 gallons, and is weatherproofed. It is bare bottomed and has two caves in it for if they decide to spawn. The water temperature is 55 degrees F, but I'll be waiting another two weeks before adding anything. I live in New England. Last year I kept white cloud minnows, but a raccoon got hungry so I moved right up against the house and rosies swim towards the bottom and I got some hornwort so I thought they'd be better suited. Will this setup work? How many to add?