Ughh common ,just cuz you have coldwater doesn't mean u are limited! Just not as big as an option compared to tropical. You can look at bass(small mouth or large mouth) a small group of them, you can look at trout preferable brook, you can also think of weather loaches,sunfish(you can get a pair and watch them breed like crazy, any types of goldfish but not koi, rainbow fish have amazing coloration! Hard to get though you prob will have to order them online, hmmm that's what I can think of for that pond, I'll post a few more once I remember somemore