any other fish good for ponds beside goldfish, koi and mosquito fish?

i just got a 300 gallon pond setup last night that the cleaning guy at work gave to me. and i have mosquito fish but i really don't like them that much, but they do a good job. so i'm looking for some other fish.

the pet store said i could put danios in it but i'm not sure, since i believe they are tropical fish. but i don't know for sure.