Butterfly koi take a few months before you can even begin to start telling they are butterfly. I have some in a aquarium that are about a 1 1/2" long and I'm just begining to tell which ones are starting to develope the longer fins. Koi normally spawn in the early early morning around day break. Depending on the size of the fish and how many eggs she's carrying, and how easy she can release will deteremine how long they lay. Just like humans, some get through delivery very easy, some take hours. It's not uncommon at all for the first spawn or two to be small. Of course the other fish follow and eat the eggs shortly after they are deposited so many hobbyist miss that part. Now, Do you have ANY goldfish in the pond? If so you may not have pure koi. Goldfish will interbreed with your koi. Very seldom will you get any real colored up babies if that happens, they are usually short stumpy fish with short fins and most will start off a brown color. They are fun to raise as well and as long as you know what fish they are they are fine kept with the others. problems start a rising when they are allowed to breed back. You'll end up with all sorts of JUNKY fish. It's a good idea to watch your fish and find out which ones are the females. (when chasing starts she'll be the front fish that all the others are harrassing) Females and males will chase a female that is laying eggs. so don't think all the chasers are males. If you have a agressive male goldfish he'll be the first to chase any female in the pond and get in there quickly to breed before the others find out there is free caviar breakfast.