Seen most often is Xiphophorus helleri, or the Green swordtail. That said, most variants commonly imported nowadays are far from green, as mass farming efforts are producing every colour under the sun ...
Matt Clarke managed to find these on sale in Dundee. Common name: Pygmy swordtail Scientific name: Xiphophorus multilineatus Origin: Endemic to the Rio Coy, Mexico. Habitat: Fast-flowing sections of ...