I have a 20 gallon aquarium with low light loving bushy plants, driftwood, and active rosy barbs and Buenos Aires tetras. I had considered putting other fish into the mix, but these small colorful, active, pugnacious (they say, semi-aggressive), archetypal, little fish are very fun to watch. I also have a 10 gallon tank with a wakin goldfish and a Shubunkin goldfish, “rescued” from the feeder fish tank at the petshop. I had a wakin goldfish in the past (as well as rosy barbs). Both tanks are at a nice equilibrium right now, but if I find another wakin goldfish for less than a dime and a nickel, the temptation to buy may be too great.