Colleen the average large koi lays over 50,000 eggs dragonfly cant be the only preditors you have if all you get is two or three survivors per year , if more than one female lays thats 100,000 etc .
Their parents will eat any eggs as well as their own fry, which they can up to 1", you may even loose a few fry canabalised by other fry
The goldfish may steal some eggs and eat some koi fry but you should still have alott of survivors as baby koi are canny when it comes to hiding out till they have grown .
Jason sorry man I keep forgetting you moved to Florida
Dave