Hello, I have a question that I’d like to ask, any answers would be greatly received. So about 2 years ago I was working at a house with a pond, the fish were spawning and there was eggs galore In the string algae, I’ve always enjoyed fishing but never kept any but for some reason had the urge to see if I could get the eggs to hatch. I asked the customer if I could take some eggs and he told me to help myself, so got a freezer bag filled it with water and put a few handfuls of the algae in took it home filled a bucket with water from my water butt and put the algae in. A few days later I had between 150-200 babies!! Anyway, cut a long story short 2 years down the line I have a 4 ft fluval with 9 fish that are about 3inches long, two are definitely gold fish the other 7 look like a goldfish but have no colour and look more like a common carp. The two that are gold and white changed colour about a year ago but the others show no sign of changing, why is this, what’s going on in my tank? The pond had koi carp, mirror carp, shubunkins and goldfish in.
It's fairly easy to tell - Koi and mirror carp have barbels near their mouth; goldfish don't. Goldfish do often change colour so there's nothing to worry about there. Long term they'd do better in a pond though as it sounds like they're not growing as much as they should.