Thanks for all the replies wasn't expecting so many so soon my pond is concrete in ground round with a stone outside facad ranges from 4 1/2 around edge to 6' in middle 26' round in ground with 1' above GL like mentioned above its cold in winter but water seems to stay around 40 on the coldest day but the summer even with a wind sail cover can get close to 90% on 100+ day some of the fish I don't think would survive the temp variance and if could hook up a heater even gas I sure would love some monster gigas it they die below 60% I'll go back and look at the fish that where mentioned thanks for replies guys