Single-tailed goldies often get to about 18" average about 12"-16" -- though some can get bigger. Koi, on the other hand, can exceed 3' in length.
http://hubpages.com/hub/Aquarium-Giants … h-Get-HUGE
Goldfish in the wild can be pretty large. Thats all they do is feed on everything and they sit on the bottom (bottom dwellers) so .. that's what makes them that big. I heard they werent even suppose to be in the wild but humans did that by releasing them. Here is a video of my goldfish.. its pretty big. http://musictunes.hubpages.com/hub/Taki … -Correctly
They are part of the Carp family and those are some of the largest freshwater fish in the world. I think they are in the top 10 in the world if that gives you an idea how large these fish have potential of getting.
Copyright © 2018 HubPages Inc. and respective owners.
Other product and company names shown may be trademarks of their respective owners.
HubPages® is a registered Service Mark of HubPages, Inc.
HubPages and Hubbers (authors) may earn revenue on this page based on affiliate relationships and advertisements with partners including Amazon, Google, and others.