Ah I see, my pond is only 70cm deep so I don't think the texas and tilapia will work. I will have to see how cold it gets this winter, and you can be sure that it gets cold here in England!when it comes to subtropical fish then only balzanii and other types of gymnogeophagus and peppered cory will survive in 0-5 celsius WATER temperature. IF there is minimum AIR temperature 5 celsius not WATER then i think texas cichlid and tilapia can make it for winter seasson. We must separate two things ,air temperature and water temperature , when air temperature is 5 celsius then water temperature at bottom of pond will be around 8 but only if you pond is deep enough - depth 1 metre and more. It wont work in shallow pond.