Goldfish carry more misinformation than almost any other pet fish, and some of it runs in directions people don’t expect. In practice, a few of the most repeated “facts” about goldfish are flatly wrong, while a few of the confident claims made to correct them turn out to be more contested than they first appear….

Goldfish health problems trace back to a small handful of root causes far more often than owners expect, and nearly all of them connect to water quality, tank size, or diet. In practice, most of what looks like a mysterious illness is actually one of a handful of well-documented conditions, several of which get confused…

Goldfish tank setups fail more often from undersizing than from any disease or water quality issue covered elsewhere on this site. In practice, most of what goes wrong traces back to a tank bought for the fish’s current size rather than the size it’s going to reach. This guide covers what equipment a real goldfish…

Comet goldfish get sold under the wrong name constantly, and the reason is simple: a bright orange common goldfish looks close enough to a comet at a glance that shops and buyers mix them up all the time. In practice, the three single-tail goldfish types covered here share a basic body plan but differ in…

Fancy goldfish types can look so different from each other that new keepers often assume they’re looking at entirely unrelated fish. In practice, every one of these varieties traces back to the same species, Carassius auratus, shaped over centuries of selective breeding in China and Japan. This guide breaks down the major types actually worth…