The Brown Goldfish

There have been goldfish swimming in our rivers, lakes and ponds since at least 1728, so it's hardly surprising that many of us have caught them and perhaps called them "crucians" because superficially they do look like their very close relative. Goldfish are Carassius auratus; crucians are Carassius carassius - same genus, different species.

If you keep goldfish in your garden pond, you'll be familiar with the dark fish that keep company with your gold, red and white ones. Those are "brown goldfish". These late developers can turn colour at any age or may just remain brown. In the wild, any that "turn" are probably more vulnerable to predators and do not often survive, but they can be found. Look at these two Danish fish, both goldfish (though the brown one is just possibly a hybrid) though you could mistake only one for a crucian! There, they are described as "gold crucians"!

Danish brown goldfish Danish goldfish

In practice, once you've handled both crucians and goldfish the differences between them quickly become clear: they are really quite dissimilar fish. Until then, though, these guidelines should help you recognize a brown goldfish:

Here's an example of an English brown goldfish. Since "gold" goldfish vary in shape, even the common ones, so it would seem logical for "brown" goldfish to do the same. Note the colour, more olive than brown, as is so often the case. Count 29 lateral line scales and 6-ish oblique from dorsal fin to lateral line. Note also the pale lower fins.

English brown goldfish

This illustration from that famous book, British Fresh-Water Fishes by the Rev. W. Houghton 1879, clearly shows that the Victorians knew what many of us have apparently forgotten, that not all goldfish are gold. Note the dorsal fin shape and the clearly forked tail.