The Longfin Blue Danio has an iridescent light blue body with long, flowing fins. This aquacultured variant is not available often. Danios are commonly recommended as “starter fish” and dither fish. They are fast and active swimmers and they like a long tank to swim in. Danios have interesting markings and are generally hardy and peaceful. These fish need a temperature of around 70°F to 75°F, so you may need a heater to regulate the water temperature.