DSC_4633 Feral swordtail (Xiphophorus helleri) Adult pair. A feral population of this tropical aquarium fish established in the Waipahihi, a geothermal stream which flows into Lake Taupo. However a recent survey has failed to find any, and so that feral population may now be extinct. 'Green' swordtails (above) apparently from the wild, are still occasionally reported from Taupo area. The particular strain depicted, was first collected in 1951 from the Rio Lancetilla, Hondurus in South America.