We have Koi and goldfish. We also noticed some small fry yesterday about 1/2'-3/4' long. At what size do koi get barbels?
I can see barbels on Koi as small as 3/4 inch - you should put them in a clear glass or plastic container and look closely. Even from a very small size, such as 3/4" you will notice that Koi are elongated, whereas Comet babies are shaped elliptically, much like a human eye.
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