Fish identification

[Newt19]

Hi, I've been part of this forum for a few years now, and you've all been great in the past when I've needed help!
We've had a pond for 6 years, it came with the house. We've recently cleaned it out, cut back the plants, repotted and generally done some maintenance on the pond.
Basically, we have fish! But I've no idea whether they are goldfish, koi or something else? I know that sounds crazy..but really, I don't know anything about fish.
When we moved in there were around 25 (bonkers, because the pond is roughly 20ft length x 4 ft width and it spans from one side of the garden to the other side - it's I think what you've call a 'formal' pond). We've rehomed fish twice now, but always get left with around 5 or 6 and they always spawn.
We have a filter. Occasionally I feed them.
I've 'googled' fish types and honestly cannot tell whether they are Koi or Goldfish.
The biggest is approx (very approx!) 15cm? Some are black (fry?), some are gold, some are multi.
Any ideas - is there a quick fire way of knowing?
Thanks all, Emma

 

[JRS]

Best bet is to catch one, koi will have barbels around the mouth; most likely goldfish due to the smaller size:

Koi Mouths | angelkoi2

www.angelkoi.com

 

[Newt19]

Thanks JRS. I'm terrible at catching them, but I can't see barbels around the mouth at all. I'm thinking (and hoping!) they are goldfish. I can try and take some photos as the water is very clear at the moment.

 

[j.w]

Some could be shubunkin goldfish if they stay multi-colored. They are quite pretty and kinda look like a small koi but don't get big like koi. I'm thinking the others are just regular goldfish. They start out brown/blackish and then turn oj or yellow or white and it can take yrs for some to turn colors.