Baby koi or baby goldfish?

[Mickowitz]

I inherited a large number of eggs along with some water hyacinth I bought; the pond they were in had both koi and goldfish. The fry now range from 1/4 to 1/2 inches long, although two are much larger than the rest. I have them in a separate baby aquarium.

I only just learned that both types are carnivorous as babies, which now explains why the school of babies went from about 6 dozen to about 3 dozen.

To me, they are all indistinguishable at this size—they are all transparent (I can see their internal organs) and basically colorless. When will they start to look different enough to tell what they are? The pond I have has shubunkins and mosquito fish.

 

[Jhn]

Koi have barbels and a downturned mouth for bottom grazing, while comets have a straight on mouth for midwater feeding.

 

[Mickowitz]

Koi have barbels and a downturned mouth for bottom grazing, while comets have a straight on mouth for midwater feeding.

Thank you, jhn—I do know how to tell them apart as adults. But how large will they have to be/how long will it take until those distinguishing features become apparent.

 

[Jhn]

Good question, never paid that close attention, to see when you can tell the difference.

 

[mrsclem]

It shouldn't be too long but the problem is that koi and goldfish will breed and the offspring are hybrids and are usually sterile.

 

[Mickowitz]

It shouldn't be too long but the problem is that koi and goldfish will breed and the offspring are hybrids and are usually sterile.

Thank you—that hadn’t even occurred to me! By saying “not too long,” is there any idea of what that could be? Six months? A year? Or how large they have to be before they start to color up and display characteristics of koi vs goldfish?

 

[mrsclem]

3-4 months and they should be a good size

 

[Mickowitz]

Cool! Can’t wait to start seeing them coloring up! thanks again mrsclem!

 

[Mmathis]

OK, been doing some research on baby koi/goldfish. Too many articles to reference (but there is a lot of info out there). These are “in general” distinctions, as all fish are going to be different. Please don’t jump on me! Not saying these are “gospel,” just what I picked up after a Google search — we all know that MOTHER NATURE does what she want, so……..

• KOI: Barbels show up after about 2 weeks of age (IOW, unless you know WHEN they were hatched, you won’t know how old they are). These are temporary and will (supposedly) disappear after a few months, before the permanent barbels grow out (never knew that about koi!).
• KOI: Most are hatched with some of their color showing.
• KOI: grow rapidly (maybe faster than GF, but I didn’t see that comparison in writing — just that they grow rapidly)
• GOLDFISH: are usually olive-colored or black when hatched, and gradually change color — some will stay black for a few seasons.
• KOI: unless specifically bread with these genetics, baby koi are rarely hatched as black
• KOI/GOLDFISH HYBRIDS: these have been classified as “ugly” — take that as you like
• KOI/GOLDFISH: body shapes differ.

My only experience with fry was when I had fry in my pond and was trying to distinguish baby GF from minnows. At that time, I got really good at picking out which was which (mainly by looking at body shape and schooling patterns). Then, my focus went to distinguishing the plain GF fry from Shubunkin fry. Apparently back in those days I didn’t have anything better to do than put baby fish in my 20gal and spend hours observing and taking pics of them for comparisons.

 

[Mgessert]

My Goldie young from this spring are starting to show color, probably about three months old.

 

[GBBUDD]

KOI CAN BE DULL for over a year then all of a sudden can start coloring up . often most are olive and then at about a year they start showing their patterns and color