I have no experience with rainbows, but I have an unstocked 20g right now and I am considering them.
Are there any species of rainbowfish that are suitable in this tank? I heard that some smaller ones like spotted blue eyes are "annuals," so does that mean I should expect them to die in a year or less? They are pricey for me, so if they are not prolific in a species-only tank I will pass them up. I'm too used to lazy livebearer tanks that replace themselves with minimal effort
Maybe sparkling gouramis are in my future...