I have a small (1500 gallon) pond in the front yard that I raise algae in. Koi, goldfish, mosquito fish, possibly a bullfrog tadpole, and one bullfrog also enjoy the cool water and pond plants.
You can't tell in this shot but most of the koi are over a foot long. The smaller fish a goldfish that I bought as 1" long "feeders". They are all about 6" long now.
Frog, one year old.
Same frog at two years old.
Summer 2006. Racoons wiped out the pond. Completely.