Well 24 hours later I still have 10 healthy looking cardinal tetras (aka neon tetras). They add a lot of movement and optical pop the tank had been missing. Now to decide what to add next. Maybe somehting a touch bigger, or something else with bright colors. Maybe half a dozen or 8 red eye tetras (Moenkhausia sanctaefilomenae). They might not have enough color to do what I want though.